Testing - Gâteau aux Noix (Caramel Walnut Cake)

From The Country Cooking of France by Anne Willan, p. 300, Gâteau Périgourdin 

http://www.cuisineaz.com/recettes/perigourdin-gateau-de-noix-36743.aspx

http://www.cahierdecuisine.com/les-recettes/gateau-perigourdin-r10204.html

https://thetoughcookie.com/2016/05/22/make-dry-caramel/

NOTE: This cake is at its best flavour if made a couple of days before serving, however, the caramel topping should be added shortly before serving as it will go soft after a few hours.

1 - I'm making this for the first time for Christmas. Because I have little luck with Ms. Willan's recipes, and I also have little luck in using egg whites to make cakes rise, for this first attempt I'm chickening out and adding baking powder. I will want to make it again but without baking powder, just to compare. Oh, and I added rum.
NOTES: The cake rose beautifully. It's a bit like a soufflé in that it puffs up higher than the cake tin, but then subsides at the later stages of cooking. The cake is quite fragile, so in the last steps when turning it out, be very careful - I tried turning it out onto a dish towel to make it easier to flip back but the top stuck to the towel and when I flipped it, it also cracked. Once it's cooled completely it is much more solid. It looks good! 

2 - This time I actually got to eat it! So good. However, it was not an unparalleled success. I used some of my early sourdough so the crumbs were too crunchy (ie hard) and the caramel topping was a complete failure - crystalized hard lump clotted on top of the cake. So, I just have to be careful with my ingredients and I'm going to change the caramel topping instructions.

3 - Yes, using proper bread creates a much more pleasant crumb. Now, I don't have a proper flat cake plate, so when I bake my cakes I put them in a regular dinner plate (well, it's a pretty flowery dinner plate with a round center but a square-ish rim, but still not flat) so the edges of the cake gets pushed up and the middle becomes a well. In pouring the caramel over, it pooled and created a thick crust that, when eating, was really awkward because the soft, moist cake would get crushed and crumbled as you tried to break through the caramel crust! Now, I have a few options

   - A) drizzle the hard caramel into threads that criss-cross and layer over the cake

   - B) either on a flat cake plate or with a spatula or both make sure the layer of caramel is quite thin

   - C) figure out a liquid caramel sauce that would soak into the cake

   - D) work out a different kind of topping

   - E) just serve with whipped cream or nothing at all

I'm consulting my lemon loaf recipe to make a caramel syrup. If this doesn't work, I will actually try it the way Anne recommends in her recipe.

2 slices day-old white bread (75-80gr, fresh)

1 cup walnut pieces (125 g?) (try grating them with a fine grater?)

Pinch of salt

2 tsps baking powder (remove for next time, to test)

1/2 cup + 2 Tbsps butter

2/3 cup sugar

1 Tbsp rum

4 eggs, separated

Grated zest of 1 lemon

For the Topping

1/3 cup (66gr) sugar

1/4 1/3 cup water

8 walnut halves

1. When you turn on the oven to preheat to 325F, put the bread in and toast it until it's very dry (about 6 minutes after your oven comes up to temperature).
2. Allow the bread to cool. Meanwhile, grease a 9" cake pan and line it with parchment paper, also buttering the paper. 
3. Once the bread has cooled grind it into fine crumbs. Add the walnuts and the salt and grind to a coarse powder (a food processor would be the easiest way to do this). Mix in the baking powder. Set aside.
4. Using the whisk attachment of a stand mixer, cream the butter, the add half the sugar. Keep whisking until the sweet butter is soft and light, 3-5 minutes.
5. With the mixer at high speed, add the rum, then, one by one, add the egg yolks, beating well and scraping down the sides after each addition.
6. Beat in the lemon zest.
7. Transfer the butter mixture to a large bowl and mix in the walnut mixture with a wooden spoon.
8. Back to the stand mixer (unless you're ambitious and like doing it by hand) in a clean bowl and with a clean whisk, beat the egg whites until stiff.
9. Gradually add the sugar and keep whisking until stiff, glossy peaks form (this is relatively quick).
10. Take 1/4 of the egg whites and mix them into the butter-and-walnut mixture. Then, dump the butter-and-walnut mixture into the egg whites and, as gently and lightly as possible, with a spatula, fold them in together.
11. Scrape the mixture into the prepared pan.
12. Bake the cake until it pulls away from the sides, and a knife comes out clean, about 40-50 minutes (one recipe recommends 30 minutes only, so start with 40 minutes). 
13. Put in an airtight container and keep for a day or two before serving (ideally).

For the Topping

1. In a small stainless steel (for the light colour) saucepan, pour in the sugar. Shake the pan to evenly distribute the caramel. The layer of sugar shouldn't be too thick to allow for the sugar to heat evenly.
2. Without any stirring (!) heat the sugar over low to medium heat until it starts to melt. This will begin at the edges and this is where caramelization starts. Be patient! DON'T turn up the heat - sugar can burn very quickly.
3. Once the sugar starts to caramelize around the edges, use a rubber spatula to bring the caramel and melted sugar into the middle of the pan.
4. Gently stir to make sure all the sugar is dissolving.
5. Once everything has dissolved, continue to slowly cook watching constantly and closely ('cause it can burn quickly) until you get the colour you want - light caramel colour = sweeter; dark caramel colour is more complex with bitter notes. 
6. And here I'm flying blind. I'm going to try adding water and cooking over low heat until dissolved. I want the caramelized sugar in liquid form so that it seeps into the cake.
7. With a skewer, pierce the hot cake in 12 places right to bottom; pour caramel syrup over the cake.
8. Put in an airtight container and keep for a day or two before serving (ideally).
9. Arrange the final 8 walnut halves on top in a pleasing pattern.
10. ?(To stop the caramelization, sit the pan in cold water and use the caramel quickly while it's hot and before it starts to harden in the pan - you're just cooling the metal of the pan so the cooking stops.)?
11. With the cake on a cookie sheet to catch the drips, pour the topping over the cake, spreading it with a spatula or other flat-ish implement to make a very thin layer. It's ok if it drips over the sides (artfully, of course).
12. Immediately afterwards decorate the cake with the walnuts.
13. When the caramel is still soft but starting to set, lightly mark out pieces - this helps in cutting the cake once the caramel has hardened.