Preheat the oven to 350°F. Prepare two 9-inch cake pans by spraying the sides with cooking spray and fitting a wax paper circle at the bottom or grease and lightly flour the pans.

Stir together the white vinegar and soy milk and set aside. Sift the cake flour and measure by spooning and leveling it in a measuring cup. Add the cake flour, baking powder, and salt to a bowl and whisk to combine. Set aside.

Pour the juice from a can of chickpeas into a medium-sized bowl. Whisk the juice vigorously for one minute until foamy. Set aside.

In a stand mixer or with a handheld mixer, cream the vegan butter with the white granulated sugar for two minutes on medium-high, scraping down the bowl and paddle once. Add 1/2 cup of the aquafaba and the vanilla extract. Mix on medium for one minute.

With the mixer on low speed, add the dry ingredients and mix until just combined. Then add the soy milk mixture in a steady stream and mix until just incorporated. Scrape down the sides and bottom of the bowl and give it a few more stirs to combine.

Pour batter evenly into prepared cake pans (no more than 2/3 of the way full) and bake for 30-35 minutes. Cakes are done when they spring back to the touch and a toothpick inserted in the middle comes out clean. Cool in the pan for five minutes before turning out onto a wire rack for cooling.

For the vegan buttercream, cream the vegan butter on medium-high until creamy and light in color, about 7 minutes.

With the mixer on low, add the powdered sugar one cup at a time, scraping down after each addition. Ensure each cup is fully incorporated before adding the next.

Add the vanilla and unsweetened dairy-free milk and mix on low for another minute until fully incorporated.

Cut out mini heart shapes from the cooled cakes using heart-shaped cookie cutters.

Color the buttercream to your liking and pipe rosettes and stars on the top of the mini cakes. Serve!