Mix All-Purpose Flour (3 cup), Granulated Sugar (1 tablespoon), and Salt (1 teaspoon) in a large bowl.
Grate the Butter (1 cup) and toss with dry ingredients.
Start to work the butter and in with your hands until the mixture starts to look buttery and the flecks of butter in the dough are pea-sized or smaller.
Drizzle in the Buttermilk (1/2 cup) and toss together with a fork until it’s too stiff to work anymore. Use your hands to fold the dough and squeeze it dough together to make one dough ball.
Shape the dough into a disk about the size of a dinner plate. Wrap in plastic wrap and place in the fridge for 30 minutes.
Roll out dough as thin as you can get it, about a 12-inch disk.
Cut rolled dough with a biscuit cutter into about 16 disks. Return to the fridge for a few minutes if the disks begin to get soft.
Preheat the oven to 400 degrees F (200 degrees C).
Mix Brown Sugar (1/2 cup), Butter (2 tablespoon), Ground Cinnamon (1/2 teaspoon), and Salt (1 pinch) together until crumbly.
Place an overflowing tablespoon of the brown sugar mixture into the center of half the dough disks.
Dip your finger in water and sweep the circumference of each disk, then sandwich one dough disk on top of the other press around the circumference with a fork.
Whisk the Egg (1) yolk and Whipping Cream (1 tablespoon) together and brush on the top of each pop tart.
Place pop tarts on a baking dish lined with parchment about one inch away from each other. Bake in the oven for 20-25 minutes until golden.
Remove from oven and let poptarts cool completely.
Mix Powdered Confectioners Sugar (1 cup), Corn Starch (1/4 cup), Whipping Cream (1/4 cup), Maple Extract (1 teaspoon), and Salt (1 pinch) together until smooth. If glaze doesn’t seem spreadable, add a little more cream about 2 teaspoons at a time and continue stirring until smooth.
Spread glaze on top of the pop tarts and sprinkle with Sea Salt Flakes (to taste).