Preheat the oven to 425° F.
Begin by sifting 3 cups flour and 1/2 tsp salt together into a large bowl.
Cut 1/2 cup butter into small cubes. Make sure it’s very cold before adding it to your flour.
Cut the butter and 2 tablespoons of lard into the dry ingredients using a pastry cutter, food processor, or your hands. You want to have very small bits of butter, pea-size or smaller. However, be careful not to overwork it. Next, slowly add the 1 1/4 cold milk into the flour mixture by stirring with a dough whisk until it is incorporated and the flour is saturated. DO NOT overwork the flour. Turn the dough onto a floured surface. Knead it 4 or 5 times until it comes together into a ball. Again, do not overwork the dough.
Lightly sprinkle flour onto the rolling pin and the surface of the dough to prevent sticking. Roll the dough out until it is around ½-inch thick.
To make the cinnamon sugar filling, combine 1/4 cup softened butter, 1/2 cup brown sugar, and 1 tablespoon of cinnamon together in a separate mixing bowl. It should have a paste-like consistency.
Using a spatula or spoon, spread the cinnamon sugar mixture in a thin layer all over the surface of the dough.
Fold the dough into thirds by taking the long end and folding it to the middle, and taking the opposite side and folding it to the middle.
Using the rolling pin, roll the dough slightly thinner until it’s around 1-inch thick.
Use a biscuit cutter or the rim of a glass to cut out the biscuits.
Place them in a cast iron skillet, or parchment paper lined baking sheet. Be sure to allow the biscuits to slightly touch. This will help them rise.
Brush the tops of the biscuits with a little milk.
Bake in the oven for 20-25 minutes or until the tops are golden brown. You don’t want to overcook them or they’ll be crunchy.
While the biscuits are baking, make the glaze by whisking together 1/2 cup powdered sugar, 2 tablespoons of milk, and 1 teaspoon of vanilla extract in a small bowl. You can add a little more milk if you want a thinner glaze.
Remove the biscuits from the oven, and allow them to cool slightly.
Pour the glaze over the tops of the biscuits.
Serve them warm and enjoy!