Grease a loaf tin (10x20cm / 4x8inches) Adjust quanitity if working with a smaller / larger tin
Beat together room temperature butter and sugar until pale then add eggs, one at a time. Mix in red food coloring
Sift in flour, baking powder, cocoa powder, salt and fold together until fully combined
Adjust color by adding more food coloring until desired red color achieved
Pipe a thin layer of red velvet cake batter on the bottom of the loaf tin then remove the heart shape pattern from freezer
Place the heart shape pattern in the middle of the loaf tin, press it down into the red velvet cake batter, then pipe the rest of the red velvet batter around the heart pattern. Make sure that the level of the batter is the same on all 4 sides of the pattern and that the heart log does not lean on any side
Bake for 45 min minutes, or until a skewer inserted into the middle of the loaf comes out clean. Take the loaf tin out of the oven, once slightly cooled move the cake over to a wire rack and allow to cool completely on it