Preheat oven to 350°F. Place 12 cupcake wrappers in cupcake tin.
In a large mixing bowl, cream butter and sugar using a hand mixer. (You can use a stand mixer for this part too if you have one.) Add eggs and vanilla, beating well.
In a separate bowl, whisk together flour, baking soda, baking powder, and salt. In a third bowl, whisk together champagne and sour cream. Gradually beat flour and champagne mixtures into butter mixture.
Divide batter evenly among cupcake wrappers and bake for 17–20 minutes. Cool completely.
To make the strawberry filling, combine strawberries and champagne in a small non-reactive saucepan over medium heat. Bring to a boil.
Once filling comes to a boil, use a wooden spoon to mash strawberries. Add sugar and continue to cook on medium heat for 10 minutes, or until sauce has thickened. Cool to room temperature.
When cupcakes and filling have cooled, you can begin to fill the cupcakes. Use a paring knife to cut a divot into the center of each cupcake. Put about a tablespoon of filling into the hole you've made, then replace divot. (If you've never done this before, read this tutorial.) Reserve 2 tablespoons of filling for frosting.
To make the frosting, combine cream cheese and butter in a large bowl using a hand or stand mixer at low speed. (If using a stand mixer, use the paddle attachment.) Once mixture is well-combined and fluffy, gradually add powdered sugar with mixer on low. When powdered sugar is fully incorporated, beat in orange zest and strawberry filling.
Pipe frosting onto cupcakes. Garnish with a small orange slices (as shown) or strawberries, if desired.
The frosting has just enough strawberry in it to give it a pink tint and a light strawberry flavor without adding food coloring or artificial flavor. If you plan on frosting your cupcakes with a spatula instead of piping it, you can add more strawberry sauce for a darker color and more intense flavor—the first time I tested this recipe, I added too much sauce to the frosting and it didn't pipe well, so I speak from experience.