In a small saucepan, add in the sugar and cornstarch. Whisk until incorporated. Add in the raspberries and champagne and whisk until combined.
Bring the mixture up to a boil and let boil for 4 minutes until thickened. Be sure to mash the raspberries with the back of a wooden spoon while it's boiling.
Place into a bowl, cover with plastic wrap and place in the fridge to chill.
Preheat oven to 350 degrees. Line a cupcake pan with liners.
Over medium heat, place a small saucepan with the 1 cup of champagne on it. Let it simmer for 17 - 20 minutes until the champagne is reduced to ½ a cup. Set aside and let cool.
In a large mixing bowl,, add in the butter, sugar and vegetable oil. Mix for 1 - 2 minutes until light and fluffy.
Add in the vanilla extract and eggs one at a time. Mix each egg until incorporated and then add the next. Scrape down the sides and mix on high for about 3 minutes until thick and very pale.
In a separate bowl, add in the flour, baking powder, and baking soda. Whisk to combine.
Begin to add the flour and champagne alternately into the butter/sugar mixture starting and ending with flour. I normally do 4 parts flour and 3 parts liquid. On the last addition of liquid, add in the 2 tablespoons of raspberry champagne filling.
Scoop the batter into the cupcake liners. Fill the liners ¾ full.
Place in the oven and bake for 18 - 20 minutes or until done. Place a toothpick into the center of the cupcake and if it comes out with moist crumbs or dry, they're done. If there's still batter, let them bake longer.
Let the cupcakes cool completely.
Once the cupcakes are cooled. take a small paring knife, and cut a hole in the center of each cupcake. Don't go all the way through the cupcakes. Depending on the size of the hole, you may need to make a second batch of filling.
Fill each cupcake with the chilled filling.
In a mixing bowl, add in the butter, powdered sugar, champagne and vanilla. Mix until incorporated.
Turn the mixer on high and beat until light and fluffy.
Place the frosting in a piping bag with a 1M tip. Pipe swirls on top of each of the cupcakes. Place a fresh raspberry on top and sprinkle with golden sprinkles.
I would recommend making a second batch of raspberry champagne filling and making large holes for the filling in the cupcakes.