Line or lightly grease a 6-inch round pan, then preheat the oven to 350°F (177°C).

In a bowl, mix the melted butter with cocoa powder until smooth. Stir in white sugar, then add egg and vanilla, and mix again.

Add flour, combine until the batter comes together, then fold in chocolate chips and a pinch of salt.

Spread the batter in the prepared pan and bake for 20 to 25 minutes, or until a toothpick inserted in the center comes out clean.

Let the brownies cool in the pan briefly, then transfer to a rack to cool completely. Once cooled, cut into small 1/2-inch chunks.

Whisk together sweetened condensed milk, vanilla extract, and half-and-half until smooth.

Mix in cocoa powder until fully blended.

In a separate bowl, whip the heavy cream until stiff peaks form, about 1 to 1 1/2 minutes.

Gently fold the chocolate mixture into the whipped cream until smooth. Then fold in the brownie pieces cautiously.

Transfer the mixture to an 8x8-inch freezer-safe container and smooth the top with a spatula.

Freeze uncovered for 3 to 5 hours, or until firm. Overnight freezing is recommended for best texture.