1. Preheat the oven to gas 4, 180°C, fan 160°C and line a muffin tin with 12 paper cases. Whisk the oil, yogurt, vanilla and eggs until smooth; set aside.
2. Mix the flour, cocoa, baking powder, bicarb and caster sugar in a mixing bowl. Make a well in the centre, pour in the wet ingredients and fold together with a metal spoon.
3. Add ¾ of the food colouring and the beetroot; mix to combine. Divide between the muffin cases. Roll 12 pieces of foil into marble-sized balls. Place the foil in each tin hole to make an indentation for the hearts, then bake for 20 mins or until a cocktail stick inserted in the centre comes out clean. Leave to cool in the tin for 10 mins, then transfer to a wire rack to cool completely.
4. Meanwhile, mix the butter, icing sugar and soft cheese in a bowl with an electric hand whisk until smooth. Spread over half the cupcakes, making a point at the bottom of the heart. Mix enough colouring through the remaining frosting to make a light pink, then use to top the remaining cakes; scatter over the sprinkles. Will keep for up to 3 days in an airtight container in the fridge.
Tip: Skip the pink food colouring to make these vegetarian.
See more Valentine's Day recipes
Freezing and defrosting guidelines
Freeze undecorated cakes. In order to enjoy optimum flavour and quality, frozen items are best used within 3 months of their freezing date. For more tips on freezing and defrosting food, read our article Love Your Freezer.