In a mixing bowl, whisk the flour, chickpea flour, cocoa, baking powder, and salt together. In another bowl, whisk the milk, espresso, sugar, eggs, canola oil, and vanilla together to combine. Pour the milk mixture into the flour mixture and whisk until just combined. Spread into the baking pan and bake in the center of the oven for 45-55 minutes or until a toothpick inserted in the center comes out clean.