In a mixing bowl, whisk together self-raising flour, baking soda, and caster sugar until well blended. In a separate bowl, mix soy milk, vegetable oil, and vanilla extract, then add apple cider vinegar at the end. Combine the wet and dry ingredients until smooth, stirring in gel food coloring. Bake at 350°F for 12-15 minutes until a toothpick comes out clean. Allow to cool and refrigerate.

Once the pink heart sponge is cooled, use a heart-shaped cookie cutter to cut out shapes from it. Place them back in the refrigerator until needed.

Prepare the cupcake batter by mixing self-raising flour, baking soda, and caster sugar in a muffin tin. In a separate bowl, whisk the wet ingredients, then combine with dry ingredients until just mixed.

Preheat your oven to 350°F. Fill cupcake liners halfway with batter, insert chilled pink hearts upright in the center, and top with more batter until liners are two-thirds full.

Bake the cupcakes for 18-20 minutes, check doneness with a toothpick. Allow to cool in the tin for a few minutes before transferring to a wire rack.

To make the frosting, beat vegan butter until light and fluffy, gradually add sifted icing sugar, and vanilla extract. Adjust consistency with soy milk if too thick.

Once cupcakes are cool, frost generously with the vegan buttercream and decorate with vegan sprinkles.