Cake
3/4 cup sugar
3/4 cup all-purpose flour
1/3 cup unsweetened cocoa powder, preferably Dutch processed
1/2 teaspoon baking soda
pinch of salt
1/2 cup buttermilk
3 tablespoons vegetable oil
1 egg, room temperature
1/2 teaspoon vanilla extract

Flan
1 (12- ounce can) evaporated milk
1 (14- ounce can) condensed milk
4 eggs
1/2 teaspoon pure vanilla extract
1/2 teaspoon salt
3/4 cup pecans, or walnuts, toasted and chopped for garnish
1 cup cajeta, homemade or store bought