Preheat oven to 350°F (176ºC). Grease an 8-inch baking pan with nonstick spray and line with parchment paper, leaving a 2-inch overhang.
Melt coconut oil and chocolate together in a double boiler (or microwave) until smooth; let cool 5 minutes.
Blend beans, eggs, sugar, cocoa, espresso powder, and vanilla in a high-powered blender until completely smooth. Add chocolate mixture and blend until smooth.
Add flour, baking powder, and baking soda and blend just until combined.
Pour batter into prepared pan, smooth top, and sprinkle with chocolate chips (if using). Bake brownies until a toothpick inserted in the center comes out clean, 25 minutes.
Let brownies cool in pan 5 minutes, then transfer to a wire rack to cool completely. Dust with powdered sugar, if desired.