Line muffin tin with baking cup liners (recipe makes 48 cupcakes, can bake in batches).
Fill each muffin tin 3/4 full. Bake in the oven for 20 minutes, or until the cupcakes are set and a toothpick inserted in the center comes out clean.
Remove from the oven and place muffins on a cooling rack. Allow to cool completely before frosting.
In a medium bowl, beat the cream cheese and butter until fully combined and fluffy (about 1 minute).
Add the icing sugar 1/2 cup at a time, and mix well, scraping the sides down with a spatula in between each batch.
Add the orange juice and Grande Marnier and mix until well combined.
Add the cornstarch and mix until well combined. If your frosting seems too thin, add more cornstarch 1 tablespoon at a time.
Fold in the zest from 1 orange. Put the frosting in the fridge for 30 minutes before using on the cupcakes.
Frost each cupcake, and serve. The frosting holds up better in the fridge, so storing the cupcakes in the refrigerator works best.
Recipe can be converted to a 3 layer cake.