Chocolate walnut tart with cajeta (surprise!)

For my first time participating in the Food Blogger event Sugar High Friday, I settled on a tart that I make every now and then. The theme is “surprise”– as in surprise ingredient or filling.

What I didn’t realize about this tart is that whenever I make this, guests are pleasantly surprised that what appears to be a chocolate tart with walnuts is really a caramel tart with a thin topping of chocolate ganache. And you can’t beat the combination of chocolate and caramel! (And for those who love walnuts, this tart is the best.)

This was originally a recipe for a chocolate caramel walnut tart out of Cooks Illustrated (my favorite cooking mag), but I’ve adjusted it in a number of ways. Ever since I mastered making cajeta, the Mexican version of dulce de leche, I try to keep some on hand (for what else? waffles, of course). This is my favorite caramel: it gives an extra layer of flavor that comes from that cinnamon-y, extra-milky flavor and texture that only cajeta has (and dulce de leche possesses as well, sans cinnamon). I also salt the walnuts and the ganache because salt is soooo good with caramel, and I’ve cut the amounts for the ganache because, well, a 9-inch tart shell just didn’t seem to have enough room for the ingredients called for.

Another thing I really like about this tart is that the crust slices perfectly. I know that seems trivial, but anyone who’s tried to slice a good ol’ American fruit pie in front of company will understand why this is important– if you want actual slices rather than a pile of crust and filling on a plate, then have a go at this tart.

Chocolate walnut tart with cajeta
makes one 9-inch tart

For extra tasty walnuts, take all the walnuts in the recipe and toast in a 350-degree oven for about 8 minutes.

Ingredients
Tart crust:
1/2 cup toasted walnuts, chopped
1/2 cup powdered sugar
1/4 teaspoon salt
1 cup all-purpose flour
1 large egg, separated
5 tablespoons cold butter, cut into 1/2 inch pieces

Cajeta and walnut filling:
1-1/2 cups cajeta (my recipe is here), or dulce de leche
1 cup toasted walnuts, chopped, sprinkled with a pinch of salt

Chocolate ganache:
1 egg yolk
4-ounces bittersweet chocolate, chopped
1 tablespoon plus 1/4-cup heavy cream
1/4 cup whole milk
pinch of salt
1 tablespoon of butter
16 walnut halves, toasted and sprinkled lightly with salt

Instructions
For tart crust:

  1. Whisk the egg white in a small bowl until frothy. Lift out 1 tablespoon of the egg white and transfer to the egg yolk. Add vanilla to the egg yolk and whisk until combined. (Set aside the remaining egg white in the fridge– you will use it later to ‘seal’ the crust.)
  2. Combine the walnuts and powdered sugar in a food processor and grind until well-combined. Add the flour and salt and process until combined. Add the cold butter until it resembles coarse bread crumbs.
  3. Add the egg yolk mixture to the food processor and run until the dough forms a ball.
  4. Remove and shape into a 6-inch disk. Wrap in plastic wrap and set in the refrigerator for 30 minutes.
  5. After 30 minutes, lightly flour two large sheets of cling wrap. Set the dough disk on one sheet, then cover with the other. Roll out dough with a rolling pin into a 13-inch sheet. Set on a baking sheet in the freezer for 15 minutes.
  6. Remove dough from freezer and peel off top layer of cling wrap. Overturn into a greased 9-inch tart pan. This dough is really forgiving, so just pat it into the pan and use the scraps that hang over the edges to make sure the crust is solid without holes or patches. Refrigerate crust in tart pan for 30 minutes.
  7. Preheat oven to 375 degrees. Place refrigerated tart pan on a baking sheet. Set a piece of foil in the crust and place pie weights in it, distributing evenly. Bake for 20 minutes. Remove the foil and pie weights and bake for an additional 10 minutes.
  8. Remove the tart shell from the oven and cool the whole thing, baking sheet and all on a cooling rack. Brush the inside of the tart shell with the reserved egg white from earlier.

For the cajeta and walnut filling:

  1. You should have approximately 1-1/2 cups of cajeta. Either let it sit at room temperature for a half hour or so, or heat it in the microwave for about 30 seconds to soften it a bit. Add the 1 cup of toasted walnuts.
  2. Pour the filling into the cooled tart shell, spreading evenly.

For the chocolate ganache:

  1. Whisk the egg yolk with the one tablespoon of cream. Set aside.
  2. Place the milk and 1/4-cup cream in a small saucepan. Bring to a simmer.
  3. Remove from heat and add the chocolate and butter. Cover for 2 minutes. Use a spatula to stir the contents until you have a smooth chocolate mixture.
  4. Stir in the egg yolk mixture until smooth.
  5. Pour the mixture over the caramel filling in the tart shell, covering the whole thing.
  6. Preheat oven to 300 degrees and bake for 25 minutes until the filling is still shiny and a bit wobbly.
  7. Arrange the salted toasted walnut halves around the perimeter of the tart.
  8. Cool on a cooling rack for 30 minutes, then refrigerate, uncovered, for 3 hours.