01 - Preheat oven to 450°F. Place butter in an 8x8-inch baking dish and melt in oven during preheating, approximately 5 minutes.
02 - Remove dish from oven, swirl butter to coat bottom evenly, and stir in peach preserves until fully combined with melted butter.
03 - Whisk flour, baking powder, sugar, and salt in large bowl until evenly distributed.
04 - Pour cold milk into dry ingredients and mix gently until just combined. Avoid overmixing to maintain tender texture.
05 - Pour dough directly over peach butter mixture in baking dish. Carefully spread to corners using spatula. Dough will appear wet and shaggy.
06 - Use greased knife or bench scraper to score dough into 9 equal squares in 3x3 grid pattern, enabling clean separation after baking.
07 - Bake for 22 to 25 minutes until top is golden brown and center is set and firm to touch.
08 - While biscuits bake, whisk powdered sugar, milk, and vanilla extract until smooth and pourable consistency achieved.
09 - Remove biscuits from oven and cool 10 minutes. Drizzle vanilla glaze generously over warm biscuits before serving.