Place 13 ounces Oreo cookies into a resealable plastic bag and gently break them up. You don't want to crush them completely but have a variation of sizes.
In a bowl, use a hand mixer to beat the softened 8 ounces cream cheese and 1/2 cup granulated sugar, together until smooth and fluffy, about 2 minutes.
Gradually pour in 1 cup heavy cream and 1 teaspoon vanilla extractContinue to beat until the mixture is combined and forms stiff peaks, 3 to 4 minutes.
In a large bowl, use a rubber spatula to fold the broken Oreos and 2 cups mini marshmallows into the cream cheese mixture until well incorporated.
Cover the bowl with plastic wrap and refrigerate for 2 hours before serving.