Preheat the oven to 325 degrees F (165 degrees C).

Sift together flour, baking soda, and salt.

Cream butter, peanut butter, and white and brown sugars. Mix in egg and 1/2 teaspoon vanilla. Stir flour mixture into creamed mixture. Shape the dough into 48 balls, 1-inch each. Place each ball in one compartment of a mini muffin tin.

For the filling, put chocolate chips in a double boiler over simmering water. Stir in milk and vanilla, mix well.

Bake in the preheated oven for 14 to 16 minutes or until lightly browned. Remove from oven and immediately make wells in the center of each using a melon baller. Cool in the pan for 5 minutes. Then carefully remove to wire racks. Using a measuring cup fill each shell with the chocolate mixture. Top with a pecan half.