Using a stand mixer with the whisk attachment or a large mixing bowl with a hand mixer, whip the heavy cream, powdered sugar, and vanilla on medium-high speed until medium peaks form. (The peaks should mostly hold their shape, but fall over a tiny bit, not a full flop over.)
Use the whipped cream right away or store it in the fridge in an airtight container for up to 24 hours. Freezing is not recommended.
Notes
How To Make Stabilized Whipped Cream (Homemade Cool Whip)Combine 1/4 cup cold water with 1 teaspoon unflavored gelatin in a small saucepan. Let that rest for 2-3 minutes. Cook over medium-low heat until the gelatin dissolves completely. Remove from the heat and allow to cool (but not solidify). Begin to prepare the whipped cream as directed above. Once the vanilla has been added, drizzle the gelatin mixture in with the mixer running on low speed. Turn up the speed on the mixer and beat to medium peaks.