Using an electric mixer or a stand mixer (with a whisk attachment) beat heavy whipping cream until thick. In a separate bowl, pour in sweetened condensed milk (and vanilla extract, if using.)
Fold (gently stir) about one cup of prepared whipped cream into the sweetened condensed milk and mix until smooth.
Pour this sweetened condensed milk/whipped cream mixture back into the bowl with the rest of whipped and gently fold together until smooth and creamy.
Next, pour half of the ice cream into a freezer safe container (a large bread baking pan works good.) Add half of the peach pie filling and use a spoon or a knife to swirl the mix-in together with the ice cream mixture.
Top peaches with remaining ice cream mixture, and then top that with the remaining peach pie filling. Swirl again. Cover with plastic wrap.
Freeze for 5-6 hours or overnight. When it is time to serve, remove from freezer and let sit on the counter to soften for 5-10 minutes prior to serving.