In a large bowl, cream together butter, sugar, peanut butter, brown sugar, and vanilla. Add the egg and beat until combined. Add in the flour, salt and baking soda and mix until just combined. Roll the dough into small balls using about 1 Tbsp. of dough each. ( You should get about 36 balls.) Place into mini muffin tins. Bake at 350 degrees for 8-10 minutes. Remove from oven, while they are still hot, use the back of a 1/2 Tbsp. and press a cup into each cookie. Once they are completely cool, fill with a dallup of Hershey's Chocolate Fudge and top with Mini M&M;'s.
