Heat milk (either in a microwave-safe dish or in a small saucepan) until it is between 115-120F (46-48C). Always stir before checking the temperature.
Pour milk into a large mixing bowl and then sprinkle yeast over top. Take a large pinch of sugar (about 1 teaspoon) and sprinkle that in as well to help the yeast grow quickly. Let sit for 5-10 minutes or until yeast has bloomed/is foamy (if it does not become foamy you will need to start over).
Once yeast is foamy, add sugars, salt, egg, and melted butter and stir until well-combined
Gradually add flour until dough is completely combined. Kneading is not required, just mix until you have dough that is well-combined.
Transfer dough to a large, lightly oiled bowl and cover tightly with plastic wrap or a clean towel. Place in a warm, draft-free place and allow to rise until doubled in size (typically 1-2 hours for me).
Once dough has risen, lightly grease a jelly roll pan (I lightly grease with a bit of butter). Turn dough out into pan and use a spatula to spread the dough over the pan, pushing the dough up the sides of the pan to form a ridge that’s about ½”- 1” (1.25-2.5cm) thick. If you need to use your fingers to manipulate the dough, it will help to lightly dust them with flour first.
Cover dough and let rise for 20-30 minutes or until increased in size by approximately 50%. Meanwhile, preheat oven to 375F (190C) and slice your peaches, if you haven’t already and prepare your egg wash by whisking together egg and 1 teaspoon water.
Once dough has risen again, layer your peaches evenly onto the cake within the ridge, slightly overlapping them and gently pressing them into the dough. You should be able to fit 3 long rows of peach slices.
Use a pastry brush to lightly but thoroughly brush the ridge of the cake with egg wash and sprinkle the ridge with granulated sugar, if desired.
Transfer to 375F (190C) oven and bake for 17-20 minutes. If you used the egg wash, your edges will be a beautiful golden brown.
While cake is still warm, prepare glaze by whisking together powdered sugar, milk, and vanilla extract. If your glaze is too thick, add another splash of milk, and if it’s too thin add a bit more sugar. The glaze should fall in a ribbon from your whisk when the whisk is lifted out of the bowl.
Drizzle glaze over warm cake.
Serve warm or allow to cool before slicing. Enjoy!