1 teaspoon vanilla
Heat oven to 350 degrees. Line 2 (9-inch) square baking pans with 14-inch-long sheets of aluminum foil, letting excess foil hang over edges. Butter foil in pans.
In a large bowl, toss together oats, flour, brown sugar, chocolate chips, coconut, baking powder and salt. In another bowl, whisk together melted butter, eggs and vanilla. Add egg mixture to oat mixture.
Stir until egg mixture is well incorporated, but don't overdo it.
Divide batter between baking pans, distributing it evenly in each pan. Bake until set, about 25 minutes, switching pans on shelves in oven about halfway through baking time. Test for doneness with a toothpick inserted in center: It should come out clean, with perhaps a few crumbs attached.
Remove pans from oven. Remove squares from pans to cooling racks, using foil to lift from pans. Cool completely before cutting each pan of squares into 16 pieces, for 32 squares total.
PS, If keeping the squares a few days before giving as gifts, don't cut them into (smaller) squares until you're ready to package them.
PB&C stands for peanut butter and chocolate, and butter and peanuts. These sensuous (if you think of food as being sexy) frosted squares are replete with virtually all the allergens: flour, two kinds of chocolate, peanuts, peanut butter … mmm.
You can make these a couple of days ahead, wrap in waxed paper, then foil and refrigerate until ready to cut and package.
1 1/2 sticks unsalted butter, plus additional softened butter for pan
6 ounces milk chocolate, chopped
4 ounces unsweetened chocolate, chopped
1 1/2 cups sugar
1 1/2 teaspoons vanilla extract
1/4 teaspoon salt
4 large eggs, at room temperature
1 cup (all-purpose) flour
1 cup roasted, salted peanuts, coarsely chopped