Preheat an oven to 350F and spray an 8x8 baking dish with nonstick cooking spray. Set aside.

Mix the dry brownie ingredients together in a large bowl. Gradually add the Greek yogurt and apple sauce until a smooth brownie batter forms. (It should be thicker than normal brownie batter.)

Add the brownie batter to the baking dish and use a spatula or spoon to spread it to the edges. 

Bake for 18-20 minutes or until the brownies are cooked through in the center. Remove to cool. 

Once the brownies have slightly cooled (5-10 minutes), use the handle of a wooden spoon or large-pronged fork to poke holes in the brownies. Pour the caramel syrup over the top as evenly as possible. 

Add the whipped topping and spread it evenly on top of the brownies. Sprinkle the toffee bits (or your choice of topping) on top. Cut the brownies into 8 squares. You can serve the protein brownies warm, but I find the dish tastes best when it's been refrigerated.