Melt the butter in a large microwave-safe bowl, then vigorously mix in the peanut butter until smooth. Blend in both sugars, then add the eggs and yolk one at a time, followed by the vanilla, mixing well after each addition.
Gradually incorporate the dry ingredients into the wet mixture until just combined, then fold in the chocolate chips. If the dough is too crumbly, consider adding a touch of milk to reach the desired consistency.
Scoop the dough into 3-tablespoon sized balls onto the prepared baking sheets, flattening them slightly. Add a few extra chocolate chips on top for a bakery-style look.
Brush oil on the zucchini. Fill the boats with the cooked minced meat, sprinkle with the cheese, and bake for 20 – 25 minutes until the cheese is melted and golden brown.