Preheat the oven to 350ºF. Spray a 9x13-inch baking dish with nonstick cooking spray, or for easy cleanup, line with foil and spray with cooking spray.

In a bowl, whisk together the flour, cinnamon, baking powder, ginger, salt, allspice, nutmeg and cloves.

In another bowl, cream the brown sugar and butter. Add the eggs and vanilla and beat to combine. Add in the dry ingredients and mix until smooth. Stir 30 of the Rolos into the batter.

Press the dough into the prepared pan. (The dough is sticky, so if needed, spray your hands with cooking spray so that you can spread it out.) Place the remaining 20 Rolos over the top of the batter, pressing them in lightly.

Bake in the preheated oven for 22 to 25 minutes, or until set around the edges but still slightly soft in the center. (The bars will continue to cook after you take them out of the oven.)