Preheat the oven to 350°F (or as specified by the brownie mix). Line a 9x9-inch baking pan with parchment paper and lightly spray with cooking spray.

Prepare the brownie batter as per the instructions on the box, pour it into the pan, and spread it out evenly. Bake according to package directions, then set aside to cool.

In a mixing bowl, whisk together the eggs, 3/4 cup of sugar, salt, and cornstarch until smooth.

In a saucepan, combine the milk and cream with the remaining 1/4 cup of sugar. Stir over medium-low heat until just about to simmer, then remove from heat.

Slowly whisk about half of the milk mixture into the egg mix to temper it.

Stir in the vanilla bean paste, then pour it all back into the saucepan. Cook over low-medium heat, stirring continuously until thickened into a pudding-like texture, which should take about 5 to 6 minutes.

Stir in the butter until it melts into the mixture.

Spread the pudding over the cooled brownies, cover with plastic wrap, and refrigerate for at least 2 to 3 hours to let it set.

When ready to serve, slice the brownies into 12 rectangles, sprinkle a little sugar on top, and use a kitchen torch to caramelize the sugar for about 30 seconds.

Let them cool slightly, then enjoy your cozy treat!