Add heavy cream and vanilla to a large mixing bowl and whisk until medium peaks form.
Pour sweetened condensed milk into whipped cream, and fold in until well combined.
In a food processor, puree strawberries and sugar until smooth.
Pour whipped cream mixture into a loaf pan using a rubber spatula to spread it out evenly.
Drizzle strawberry puree over the top of the cream mixture. Use knife to cut the puree into the cream mixture, running it back and forth through the puree until it's all swirled in with the cream mixture. You don't want to completely combine the pure it!
Cover the pan with plastic wrap and freeze overnight, or for 8 hours until set.