Preheat your oven to 350°F (175°C).

In a mixing bowl, cream together the softened butter, granulated sugar, and brown sugar until smooth.

Beat in the eggs one at a time, followed by the vanilla extract.

In a separate bowl, whisk together the flour, baking soda, and salt.

Gradually add the dry mixture to the wet ingredients, mixing until just combined.

Gently fold in the chocolate chips or your chosen filling.

Grease the muffin tin lightly.

Drop spoonfuls of dough into each muffin cup, filling them about halfway.

Bake in the preheated oven for 10-12 minutes until edges are golden and centers are soft.