Preheat and prep: Heat oven to 350°F (175°C). Lightly grease a mini muffin tin (24-cup) with nonstick spray or butter.

Mix dry ingredients: In a bowl, whisk flour, baking soda, and salt. Set aside.

Cream butter and sugars: In a large bowl, beat butter, granulated sugar, and brown sugar until light and fluffy, about 2 minutes.

Add egg and vanilla: Beat in the egg and vanilla until smooth, scraping the bowl as needed.

Combine: Add dry ingredients to the wet in two additions. Mix just until no dry spots remain. Fold in mini chocolate chips if using.

Portion: Scoop 1 tablespoon of dough into each mini muffin cup. Press gently to create a shallow well.

Bake base: Bake 8–9 minutes, until the edges are set but centers still look soft. Remove from the oven.

Stuff with chocolate: While hot, press one piece of chocolate into the center of each cup. The heat will soften it.

Add mini eggs: Immediately press 1–2 mini eggs on top of the softened chocolate in each cup.

Set and cool: Let the cookie cups cool in the pan for 10 minutes. Use a butter knife to gently lift each one out to a rack. Cool completely so the centers firm up.

Serve: Enjoy slightly warm for a gooey center or fully cooled for clean bites and extra crunch.