Preheat the oven to 375° F. Stir together the flour, baking soda and salt in a small bowl. Beat butter, granulated sugar, brown sugar, eggs and vanilla in a large mixing bowl. Gradually beat in flour mixture. Stir in oats.

Spray a mini muffin tin with cooking spray, then press the dough into all the bottoms and sides.

Bake 6 to 8 minutes, or until they're lightly browned. When they come out of the oven, use a spoon to press the sides and bottoms of the cookies down--they'll puff up a little during baking. Let cool completely.

While they're cooling, add the butterscotch chips, 2 T. butter, and heavy cream to a microwaveable glass bowl. Microwave for 30 seconds, stir well, then in 10 second intervals until you can stir it completely smooth.

Once the cookies are cool, use a table knife to go around the edges and loosen and remove them. Place a on a plate, then fill each one carefully with the butterscotch ganache. Let the ganache set before serving.