Preheat the oven to 350°F (175°C) and prepare the cupcake pan.
In a mixing bowl, whisk together the flour, baking powder, baking soda, and salt.
In another bowl, cream together the softened butter and sugar until light and fluffy.
Add the eggs, one at a time, mixing well after each addition.
Stir in the lemon zest and lemon juice, followed by the milk.
Gradually add the dry mixture to the wet ingredients, stirring until just combined.
Prepare the raspberry swirl by mashing the raspberries and mixing them with cornstarch.
Distribute the cupcake batter into the prepared pan evenly.
Spoon dollops of the raspberry mix on top of the batter, then swirl with a toothpick.
Bake in the preheated oven for 18-20 minutes, or until a toothpick inserted comes out clean.
Allow the cupcakes to cool in the pan for 10 minutes before transferring them to a wire rack.
Serve and enjoy your Lemon Heaven Cupcakes with Raspberry Swirl.