Line a 13- by 9-inch glass pan with parchment paper, leaving a 2-inch overhang and spray with nonstick spray.
Whisk flour and salt together in a small bowl and set aside.
In a large bowl, using a hand held mixer, cream butter and both sugars together until light and fluffy. Slowly add eggs, 1 at a time until thoroughly combined. Add milk, vanilla extract, and peanut butter and continue to mix. Incorporate dry mixture into wet mixture in 3 separate additions. Using a spatula, fold in chocolate covered toffee bits.
Pour batter into prepared pan. Bake in the center rack of the oven for 30 minutes. Remove when toothpick inserted in the center comes out clean. Transfer to a wire rack and allow to cool completely. When cool use cookie cutters to create fun shapes.