Preheat your oven to 350 degrees Fahrenheit. Line a muffin pan with baking liners.
If you haven't prepared the chocolate truffles yet, go ahead and do that now. You can freeze them while you prepare the cupcakes.
In a medium bowl, whisk together 1 1/4 cups all-purpose flour, 1 1/2 teaspoons baking powder, and 1/4 teaspoon salt. Set aside.
In a large mixing bowl, beat together 3/4 cup granulated sugar and 6 tablespoons unsalted butter on medium-high speed until light and fluffy, about two to three minutes.
Reduce the mixer speed and add in 1 large egg and 1 egg white one at a time, mixing well after each addition. Stir in 2 teaspoons vanilla extract.
Gradually add the flour mixture to the wet ingredients, alternating with 1/2 cup whole milk, starting and ending with the flour mixture. Mix until just combined.
Divide half of the batter among the lined muffin cups, filling each about halfway.
Place a frozen chocolate truffle in the center of each filled liner. Cover with the remaining batter.
Bake in the oven for 15 to 18 minutes or until the tops are lightly golden and a toothpick comes out clean. Let cool completely.
For the frosting, beat together 1/2 cup unsalted butter, 3 cups powdered sugar, 2-3 tablespoons of milk, 2 teaspoons vanilla extract, and 1/4 teaspoon salt until smooth and fluffy.
Frost the cooled cupcakes generously and decorate with your favorite toppings!