Place metal or freezer safe glass loaf dish in the freezer.
In a medium sized bowl (you can use a stand mixer), using a whisk or the whisk attachments for your mixer, whisk the heavy cream and vanilla. Continue whipping until stiff peaks forms, about 2-5 minutes.
Using a rubber spatula, fold in the sweetened condensed milk.
Separate mixture into two bowls. Add blue food coloring to one.
Remove the loaf pan from the freezer and add in the white and blue ice cream mixture. I like to alternate adding each ¼ cup at a time to get a good color layering system going.
Take a knife and drag it through your mixture a few times, swirling it about, then cover with plastic wrap and freeze for 5-6 hours.