01 - Preheat oven to 450°F. Place butter in an 8x8-inch baking dish and put in oven to melt while preheating, about 5 minutes.
02 - Remove dish from oven, swirl to coat bottom, and stir in peach preserves to combine with melted butter. Set aside.
03 - In a large bowl, whisk together flour, baking powder, sugar, and salt until well combined.
04 - Pour cold milk into dry ingredients and gently mix until just combined. Do not overmix—the dough will be wet and shaggy.
05 - Pour biscuit dough directly over peach butter in baking dish. Carefully spread dough evenly to corners.
06 - Using a lightly greased knife or bench scraper, score dough into 9 squares in a 3x3 grid to help biscuits pull apart after baking.
07 - Bake for 22 to 25 minutes until golden brown on top and set in the center.
08 - While biscuits bake, whisk together powdered sugar, milk, and vanilla extract until smooth and pourable.
09 - Remove biscuits from oven and cool for 10 minutes. Drizzle vanilla glaze generously over warm biscuits before serving.