Preheat the oven to 425 degrees F (220 degrees C). Line a baking sheet with parchment paper and set aside
Sift flour, 4 1/2 teaspoons sugar, baking powder, and salt together in a bowl. Rub in butter with your fingers until mixture resembles course crumbs. Stir in 1/2 cup milk and mix into a soft dough.
Divide dough into 4 equal parts and flatten each part into a 2-inch diameter disc. Place on the prepared baking sheet. Brush the tops with 1 tablespoon milk.
Mix remaining 1 teaspoon sugar and cinnamon in a small bowl. Sprinkle the top of each biscuit with cinnamon sugar.
Bake in the preheated oven until biscuits begin to brown on the edges, about 12 minutes. Cool on a wire rack.
Meanwhile, whisk water, sugar, cornstarch, and cinnamon together in a medium saucepan over medium heat. Add sliced peaches and cook until sauce begins to thicken, stirring occasionally to coat all of the peaches. Remove from heat and cool.
Whip heavy cream in a bowl until stiff peaks form.
Cut each biscuit in half horizontally. Place the bottoms on a serving plate. Add a dollop of whipped cream, top with 1/4 of the peaches, another dollop of whipped cream, and the biscuit top. Serve immediately.