Before you start preparing the recipe, make sure all your ingredients are at room temperature.
Grease and flour two 15 cm heart-shaped pans. Preheat the oven to 175°C (350°F).
Mix the milk with the vinegar and vanilla. Reserve.
In a large bowl, mix the flour, cornstarch, sugar, baking powder, baking soda, salt. Proceed to sift them. Add oil, margarine and mix until you get some kind of cookie dough (make sure there are no unmixed flour lumps). Reserve.
Mix the aquafaba with the cream of tartar and whisk until very foamy (about 4 minutes). Reserve.
Add the milk mixture to the flour mixture and beat until smooth. Add the aquafaba and beat again until completely integrated.
If you want the cake to have a little touch of pink inside, reserve ¼ part of the batter and, in equal portions, pour the mixture into the previously greased and floured pans.
To the ¼ part that you reserved, add a little red or pink food coloring and mix. Divide it between the two pans and give it a little swirl with a toothpick.
Bake for approximately 20 minutes or until a toothpick or knife inserted into the center of the cake comes out clean.
Once cooked, remove from the oven, and let them cool for 10-15 minutes (still in the pans). Then, tap the molds lightly to loosen them and separate the sponge from the pan; place a rack on top and flip them over.
Let them cool completely before assembling.
Fill the cake with mixed berry jam, vanilla buttercream and decorate in a vintage style as shown in the recipe video (we really recommend watching the video so you get a similar result to the photos).