Place drained beans in the work bowl of a food processor and puree.
Add the eggs, vegan sugar, baking powder, and lemon zest to the puree, and pulse processor a few times just to combine ingredients well.
Preheat oven to 350.
Pam a 9 cake pan. Cut a round of wax paper to fit bottom of pan, place in bottom, and spray top of paper. Pour in batter.
Bake on center rack of oven for 45 minutes or until a knife inserted in the center comes out dry.
Set on wire rack to cool for 15 minutes, then remove cake from pan and allow to cool to room temp.
Before serving, squeeze lemon juice over cake, and sprinkle generously with confectioners vegan sugar.