Preheat the oven to 175°C. Prepare a standard chocolate batter using cocoa powder and half of the base ingredients. Spread into a shallow baking tray lined with parchment paper and bake for 15-18 minutes until set.

Once cooled, use a heart-shaped cutter to stamp out chocolate hearts and freeze for 20 minutes.

In a stand mixer, beat softened butter and sugar at medium-high speed for 5 minutes until pale and fluffy.

Add eggs one at a time, ensuring stable emulsification.

Sift cake flour and baking powder over the mixture and fold gently.

Stream in whole milk and vanilla paste, achieving a 'dropping consistency.'

Pour 1 inch of vanilla batter into the bottom of a greased loaf pan.

Stand the frozen chocolate hearts upright in a continuous row down the center of the pan.

Pipe the remaining vanilla batter around the sides and over the top of the chocolate hearts.

Bake at 170°C for 45-50 minutes, checking internal temperature reaches 98°C.

Let the cake rest in the pan for 10 minutes before transferring to a wire rack.

Cool completely before slicing.