01 - Preheat oven to 450°F. Place butter in an 8x8-inch baking dish and melt in oven during preheating, approximately 5 minutes. Remove dish, swirl to coat bottom, and stir in peach preserves until combined with melted butter.
02 - Whisk flour, baking powder, sugar, and salt in a large bowl. Pour in cold milk and gently mix until just combined. Avoid overmixing to ensure tender biscuits.
03 - Pour biscuit dough directly over peach butter in baking dish. Carefully spread dough evenly to corners. Using a lightly greased knife or bench scraper, score dough into 9 squares in a 3x3 grid pattern.
04 - Bake for 22-25 minutes until surface is golden brown and center is set. The swim method creates a crispy, buttery bottom edge.
05 - While biscuits bake, whisk powdered sugar, milk, and vanilla extract until smooth and pourable. Adjust consistency with additional milk if needed.
06 - Remove biscuits from oven and cool for 10 minutes. Drizzle vanilla glaze generously over warm biscuits. Serve immediately for optimal texture.