Melt butter, shortening, and peanut butter together in the microwave in a microwave safe bowl. Stir in brown and white sugar. Add egg and vanilla, stir to combine. Sprinkle in baking soda. Stir in flour a little at a time until a thick dough is formed.

Scoop even sized teaspoonfuls onto a greased cookie sheet. Bake at 350 degrees for 8-10 minutes. You want a soft cookie with just a hint of crispiness around the edges.