Dissolve 1 cup of dark baking cocoa in 1 cup of very hot milk. Whisk in 1 cup of hot espresso. Set mixture aside to cool completely. Mix together 2 3/4 cup wheat-free flour mixture, 1/2 tsp salt, and 1 tsp baking soda. Set aside. On low speed, cream 1 1/2 sticks butter adding 3/4 cup canola oil and 1 1/2 cups sugar in small amounts, mixing constantly to form soft peaks. Mix in 4 large eggs, one at a time. Make batter by adding chocolate mixture and dry ingredients in alternating thirds to creamed butter and sugar mixture. Mix until just combined. Pour batter immediately into prepared 8 inch round cake pans and let stand at room temperature for 8-10 minutes. Bake for 40-50 minutes at 350ᵒF.