Preheat the oven to 160°C Fan/180°C/350°F/Gas Mark 4. Grease and line a 2lb loaf tin.

Make the pink sponge: In a mixing bowl, combine the softened baking spread and caster sugar. Beat until fluffy and light (about 3 minutes). Add eggs and vanilla extract, mixing until combined.

Fold in self-raising flour and pink food coloring until desired shade is achieved. Pour into the prepared loaf tin and bake for about 50 minutes, or until a skewer comes out clean.

Cool the pink sponge completely, trim the ends, and cut hearts using a heart-shaped cutter.

Make the chocolate sponge: In a clean mixing bowl, mix baking spread and sugar for about 3 minutes until fluffy. Incorporate eggs and milk, mixing until smooth.

Sift and fold in self-raising flour, cocoa powder, and baking powder. Spread about 2 tablespoons of the mixture on the bottom of the loaf tin.

Arrange the pink sponge hearts in a row over the chocolate sponge layer. Spoon the remaining chocolate batter around and on top of the pink sponge hearts.

Bake for an additional 50 minutes or until a skewer comes out clean.

Beat the softened unsalted butter alone for 2 minutes. Add icing sugar, vanilla extract, and milk, mix until combined.

Fold in the melted dark chocolate until smooth. Adjust with more milk if necessary.

Once cooled, spread or pipe the buttercream over the top of the cake and sprinkle with heart sprinkles if desired.

Slice to reveal the hidden heart design.