In a large bowl, combine flour, sugar, salt, and instant yeast. Add warm milk, melted butter, and egg. Knead for 6-8 minutes until smooth. Cover and let rise for about 1 hour.

In a saucepan, combine diced peaches, brown sugar, cinnamon, cornstarch, and vanilla. Cook over medium heat for 5-7 minutes until thickened. Let cool.

After dough has risen, roll it into a 12x18-inch rectangle. Spread butter, then sprinkle brown sugar and cinnamon mixture. Spoon cooled peach filling evenly over dough.

Roll the dough tightly from the long edge into a log. Slice into 12 equal rolls and place in a greased 9x13 dish.

Cover and let rise for another 30-45 minutes or refrigerate overnight. Bring to room temperature before baking.

Preheat oven to 350°F. Once rolls have risen, bake for 25-30 minutes until golden brown.

Whisk powdered sugar with milk for glaze. Drizzle over warm rolls and serve.