A Little Slice of Heaven

1-1/2 cups Nutella, divided
1/3 cup salted butter, softened
1/2 cup light brown sugar, packed
2 large eggs
3 teaspoons vanilla extract
1/2 teaspoon Kosher salt
3/4 cup all-purpose flour

Preheat oven to 350 degrees.
Line an 8x8-inch baking pan with parchment paper or simply spray with cooking spray.
Using a stand mixer with paddle attachment, cream the butter and brown sugar together at medium speed until well combined, about 2 minutes. Add the vanilla, salt, and eggs, mixing until smooth, about 5 minutes. Add 1-1/4 cups of the Nutella and mix until smooth. Lower the speed to low and add the flour, mixing until just combined. Place the batter into the prepared pan and spread it out as evenly as possible. Add the remaining 1/4 cup Nutella to a zip-top bag snipping off a small piece of the corner. Squeeze the Nutella in quarter-sized drops on top of the batter and swirl into the batter using a metal skewer or a butter knife. Place pan in the oven and bake for 30 to 33 minutes. Cool completely before cutting.