Place your mixing bowl and beaters in the refrigerator for about 10 minutes. Cold equipment helps the cream whip faster. Make sure your heavy cream is also very cold before starting.

Pour the cold heavy cream into the chilled bowl. Beat it on medium speed until soft peaks form. Do not overbeat the cream, or the filling may become heavy and grainy.

Slowly pour the sweetened condensed milk into the whipped cream. Add the vanilla extract and powdered sugar. Gently mix until everything is combined and the filling looks smooth.

Use a rubber spatula to fold the mixture gently. Scrape the bottom and sides of the bowl as you fold. This keeps the mixture light while blending every ingredient evenly.

Fold in mini chocolate chips if you want extra chocolate flavor. You can skip them for a classic vanilla filling. Keep the mixture creamy and avoid stirring too much.

Place half of your cookies on a parchment-lined tray. Spoon an even layer of filling onto each cookie. Gently spread it toward the edges without pressing too hard.

Place another cookie over each filling layer. Press very gently to create an even sandwich. Wipe away extra filling around the edges for a cleaner homemade look.

Cover the tray tightly with plastic wrap or foil. Freeze the sandwiches for at least six hours. Overnight freezing works even better and gives the filling a firm and creamy texture.