Preheat the oven to 400 degrees. Toss the strawberries, brown sugar, 1 teaspoon of vanilla bean paste and pinch of salt on a sheet pan. Roast in the oven, tossing occasionally, for 15 minutes. The juices should release. Scrape the contents of the pan into a blender or food processor and allow to cool briefly. Cover the hot mixture with a lid and carefully pulse the until all of the large strawberry pieces have been broken down and the mixture is now a thick, chunky puree. Set aside.
In a large bowl, combine the buttermilk, heavy cream, simple syrup, and remaining vanilla bean paste. Whisk until combined. Transfer the mixture to a liquid measuring cup or something you can easily pour with. Pour the buttermilk mixture into your prepared popsicle molds, filling the mold until they are about 2/3 of the way full. Top the buttermilk mixture with a bit of the strawberry mixture, being sure to not overfill. Insert your popsicle sticks and freeze according to the popsicle mold instructions for at least 7 hours or until frozen solid. Enjoy frozen!
You can purchase simple syrup at the store, but I make my own. Combine equal parts water and sugar in a saucepan on the stove over medium heat. Stir occasionally, cooking until the sugar has dissolved. Allow to cool in a heat safe container. I usually cook 1 cup of water and 1 cup of sugar and store in a mason jar in my fridge.
If your popsicle mold is larger or smaller than mine, this recipe will yield different amounts. The recipe as written will make 10-2.5 ounces popsicles. When pouring your molds, be sure to make your popsicles about 2/3 buttermilk mixture and 1/3 strawberries. You can also swirl the two together if you’d like.