Beat butter, brown sugar, and sweetener in a large bowl until light and fluffy. Beat almond butter, egg, milk, honey, and vanilla extract into butter mixture until smooth. Stir all-purpose flour, whole wheat flour, salt, and baking soda into almond butter mixture; fold in toffee bits until dough is just combined.
Roll the dough into walnut-sized balls and place 2 inches apart on baking sheets. Press and flatten balls with a fork, creating a crosshatch.
Bake in preheated oven until golden brown, 8 to 12 minutes.