Preheat your oven to 350°F and line a 9x9-inch square pan with parchment paper.
In a large mixing bowl, use a hand mixer on high to cream together sweetened condensed milk, butter, and sugar until thick and smooth (about 3-5 minutes).
14 ounces sweetened condensed milk, ¼ cup unsalted butter, softened, ¾ cup granulated sugar
Add the eggs and vanilla extract and mix again on high to combine.
2 large eggs, 2 teaspoons vanilla extract
Next, add the flour, cocoa powder, and salt and mix again until there are no visible clumps.
½ cup all-purpose flour, ½ cup unsweetened cocoa powder, ¼ teaspoon salt
Transfer batter to your lined pan and pour chocolate chips on top.
1 cup chocolate chips (dark or semi-sweet)
Bake for 35-45 minutes. Give the pan a little shake. You'll know they are ready when the center wobbles, but the edges are set. Make sure to allow them to cool completely before slicing and peeling away from parchment paper (they change texture as they cool). Sprinkle on a pinch of salt (optional).
1 pinch sea salt on top