Preheat the oven to 350°F (180°C). Grease an 8-inch (1.2 L) round cake pan with coconut oil. Line the bottom of the pan with a circle of parchment paper.
In a high-speed blender, add the lemon zest, lemon juice, white beans, maple syrup, olive oil, oat milk, vanilla, and almond extract. Purée until smooth, about 1 to 2 minutes.
In a large bowl, whisk together the almond flour, all-purpose flour, flaxseed, baking powder, and salt. Add the wet ingredients to the dry ingredients and stir to blend. Pour the batter into the prepared cake pan and smooth the top. Bake for 45 minutes, until the cake is lightly golden on top and a toothpick inserted into the centre of the cake comes out clean. A bit of cracking is normal. Let the cake cool in the pan for 10 minutes. Invert the pan over a plate and tap the bottom to dislodge the cake. Transfer the cake to a rack to cool completely before slicing. Store loosely covered on the counter for up to 4 days.