Champagne-Vanilla Cupcakes

Name: Champagne-Vanilla Cupcakes
Cook time: 1 h
Total time: 1 h
Cuisine: American
Ingredients: 1 half-bottle (375 ml) champagne or other sparkling wine (about 1 1/2 cups); 1 teaspoon pure vanilla extract; 1 cup all-purpose flour; 1 1/2 teaspoons baking powder; 1/2 teaspoon kosher salt; 6 tablespoons unsalted butter, at room temperature; 3/4 cup sugar; 1 vanilla bean, split lengthwise and seeds scraped (pod reserved for the frosting); 1 large egg, separated; 2 teaspoons unflavored gelatin powder; 1/2 cup sugar; 1/4 teaspoon kosher salt; 4 large egg yolks; 1/2 cup cold heavy cream; Sugar pearls, for decorating