These are yummy and they keep their shape:
1/2 cup butter
1/4 cup vegetable oil
1 cup sugar
1/2 cup smooth peanut butter
1 large egg
1/2 tsp. vanilla
2 cups flour
1/4 cup finely crushed corn flakes
1/8 tsp. salt
Preheat oven to 350. Cream together the butter, oil, and sugar until fluffy. Add peanut butter, egg, and vanilla. Beat until smooth. In separate bowl, combine flour, cereal, and salt. Add dry ingredients to creamed mixture. Stir until a soft dough forms. On floured surface, roll to 1/4" thickness. Cut into shapes and transfer to a greased cookie sheet. Bake 10-12 minutes or until edges are light brown.
Note: this dough is easy to work with, but it is very soft. To keep the shape of the cutter, I roll the dough onto parchment paper. I then cut out the shapes, remove the excess dough, then transfer the entire sheet of parchment to a cookie sheet.