These are SO good, and SO easy. They can be made with any favorite brownie recipe. Bake 'em in an 8" or 9" square pan, but prepare enough batter for a 9x13" pan. I doubled my standard recipe. Line the pan with foil and spray it with cooking spray. Pour in half the batter or a little less. Dot with peanut butter cups. You can use big or small ones, and they don't need to be cut up. Leaving them whole is what gets you the nice, peanut buttery middle layer. I used Trader Joe's dark peanut butter cups, and I offset them a little so you get a bite of peanut butter in every brownie. Pour the rest of the batter over, and bake. These will take longer than your usual bake time because they are so much thicker. When they are reasonably firm on top, and not jiggly, they're probably done. Don't leave them in too long, at the risk of over-baking. However, the first time I made them, I significantly under-baked them to the extent that they were pure fudge all the way through. While I did bake them a few minutes longer this time, don't think there was a crumb left of that first batch: we soldiered through.
This is my standard brownie recipe: Steffi's Brownies. I could swear I'd posted it here before, but I can't find it, so I'll repost it for your convenience.
Peanut Butter Cup Brownies
Makes an 8" or 9" square pan, about 25 brownies
2 sticks butter
4 ounces (4 squares) unsweetened chocolate
2 cups (14 ounces) sugar
1 teaspoon vanilla
1 1/4 cups (5 1/4 ounces) flour
2 pinches of salt
18-20 mini or 9-10 regular-sized peanut butter cups
*1 cup (6 ounces) chocolate chips (or 1 cup chopped nuts, but that's not my preference)
Preheat the oven to 350F. Line an 8" pan, 9" pan, or 9x13" pan with foil, and spray it lightly with cooking spray. (See notes below about which pan to use.)
In a large, microwave-safe bowl, melt the butter and unsweetened chocolate. Stir to incorporate fully, and set aside to cool for three minutes. Stir in sugar, then vanilla, and mix well. Add the eggs, one at a time, stirring well after each addition. Stir in the flour and salt.
If you are making peanut butter cup brownies, pour about half the batter into the 8" or 9" pan. Dot with whole peanut butter cups. Pour the rest of the batter over. Bake for 25-30 minutes or until brownies are relatively firm and not jiggly. You can try the toothpick test (it should come out clean, but not dry), but you may hit a peanut butter cup and have a hard time telling if they are done. Cool in the pan, then use the tinfoil to lift the brownies out of the pan. Cut with a thin knife. These are so tall and rich that even a small pan can easily yield 25 brownies.
*If you want to make regular brownies, omit the peanut butter cups. Stir the chocolate chips into the brownie batter, then pour into the 9x13" pan. Bake for 20-25 minutes, and err on the side of underbaking. I usually start checking them around 18 minutes. Let the brownies cool in the pan until they are cool to the touch, then use the tinfoil to lift them out onto a cutting board and cool them completely. Cool in the pan, then use the tinfoil to lift the brownies out of the pan. Cut with a thin knife.
Print this recipe.
ETA: I entered these in Meg's Valentine's brownie contest. They are definitely not cakey!