Preheat oven to 375°F. Lightly coat a 7-by-11-inch baking dish with cooking spray. Whisk milk, yogurt, ⅓ cup peanut butter, eggs, pudding mix, maple syrup, vanilla, baking powder, salt and baking soda together in a large bowl until combined.
Fold in oats and chocolate chips until evenly coated. Transfer the mixture to the prepared baking dish. Microwave the remaining ⅓ cup peanut butter on High until warmed and runny, about 1 minute. Drizzle evenly over the oat mixture.
Bake until just set in the center and a wooden pick inserted in the center comes out clean, 35 to 45 minutes. Transfer to a wire rack and let cool for 10 minutes before slicing and serving. Additional reporting by Carrie Myers, M.S. and Linda Frahm