Preheat the oven to 350°F (175°C). Line a 12-cup muffin tin with cupcake liners.
In a large mixing bowl, beat 1 cup softened butter, granulated sugar, and brown sugar together with an electric mixer on medium speed until creamy and smooth, about 2-3 minutes.
Add the eggs one at a time, beating well after each addition. Mix in 2 teaspoons vanilla extract.
In a separate bowl, whisk together the all-purpose flour, baking soda, and salt.
Gradually add the dry ingredients to the wet ingredients, mixing on low speed until just combined.
Fold in 2 cups semisweet chocolate chips evenly into the cookie dough.
Scoop the cookie dough into the prepared muffin tin, filling each cup about 3/4 full.
Bake for 16-18 minutes or until the edges are golden and a toothpick inserted into the center comes out clean or with a few moist crumbs.
Remove the cupcakes from the oven and allow them to cool in the pan for 5 minutes, then transfer to a wire rack to cool completely.
While the cupcakes cool, prepare the frosting. Beat 1/2 cup softened butter with an electric mixer until creamy.
Gradually add powdered sugar, mixing on low speed until combined.
Add milk and 1 teaspoon vanilla extract, then beat on medium-high speed for 2-3 minutes until light and fluffy.
Once cupcakes are completely cool, frost each cupcake generously with the vanilla buttercream frosting.
Sprinkle 1/4 cup semisweet chocolate chips on top of the frosted cupcakes as garnish.
Serve immediately or store as directed.