Fudge Brownies with Spicy Peanut Butter Swirl

My picture of these brownies will be a bit misleading because I know I had some kind of user error, leading the swirl to be more of a full-on layer, not baking very quickly, possibly overbaking the rest, and so on. But I really like the concept, I thought they still tasted great in the end, so I will encourage you to check out the cookbook and the recipe and see if you can do better than me. (I'm pretty sure it was the peanut butter I used!) This comes from Food Between Friends by Jesse Taylor Ferguson and Julie Tanous.

Fudge Brownies with Spicy Peanut Butter Swirl

Spicy Peanut Butter Swirl

3 tbsp unsalted butter, melted
1/2 cup crunchy peanut butter (regular old supermarket brands, not the natural stuff)
1/4 cup confectioners' sugar
1/2 tsp ground cinnamon
1/2 tsp cayenne pepper
1/4 tsp kosher salt

Brownies

Nonstick cooking spray
10 tbsp unsalted butter
5 oz 70-72% dark chocolate, finely chopped
1 1/4 cups granulated sugar
2 tbsp unsweetened cocoa powder
1/2 tsp kosher salt
1 tsp vanilla extract
3 large eggs, room temperature
1 cup all-purpose flour

1. Make the peanut butter swirl: In a medium bowl, whisk together the melted butter, peanut butter, confectioners' sugar, cinnamon, cayenne, and salt until smooth. 
2. Make the brownies: Preheat the oven to 350 F. Line a 9-inch square cake pan or baking dish with parchment paper, leaving a 1-inch overhang. Coat with nonstick cooking spray.
3. Combine the butter and chocolate in a large, heatproof bowl. Melt in the microwave until smooth, stirring every 30 seconds, about 1 minute total. Add the sugar, cocoa powder, salt, and vanilla and whisk until smooth. Add the eggs, one at a time, whisking well after each addition. Use a rubber spatula to fold in the flour. Do not overmix.
4. Transfer the batter to the baking dish. Dollop the peanut butter mixture on top of the brownie batter and use a butter knife to swirl it through. Bake until a toothpick inserted in the center comes out almost clean, but with a few moist crumbs attached, 25-30 minutes. Let cool completely in the pan before cutting into 16 brownies.