To make the dough:

1. Pour the milk in a small saucepan. Bring to a simmer and add the butter. Remove the saucepan from the heat and stir in the butter until it is melted. Let cool until the mixture is warm to the touch (not hot).
2. Place the yeast, sugar and salt in the bowl of a stand mixer. Add the warm milk and butter mixture. Stir to mix. Let sit 10-15 minutes, until the yeast has bloomed (there should be a puffed light brown yeast topping).
3. Fit the stand mixer with the dough hook attachment. Add the egg to the warm milk/yeast mixture and run the stand mixer on low until the egg is incorporated. Add the flour to the mixture, ½ cup at a time, with the mixer running on low, until a ball of dough has formed. Let the mixer run on low to knead the dough, 2-3 minutes.
4. Coat a large glass bowl with cooking spray. Set aside. Dust a large cutting board with about ¼ cup of flour. Transfer the dough to the cutting board. Knead the dough for 1-2 minutes or until a smooth ball forms. Transfer the dough ball to the greased glass bowl. Cover with plastic wrap and let sit 1 hour or until the ball has doubled in size.

To make the filling:

1. Place the butter in a large skillet on medium heat. Add the diced apples, lemon juice, brown sugar, cinnamon and salt and bring to a low simmer. Let the apples cook until soft, about 5-6 minutes, stirring occasionally. Stir in the walnuts (if using) and let cook another 1-2 minutes. Let the apple filling sit until the dough is ready.

To make the bread:

1. Transfer the proofed dough to back to the cutting board, adding additional flour to the board if needed (so the dough doesn’t stick). Press the dough out into a ½-1 inch circle.
2. Place a piece of parchment paper into a Dutch oven or large round high-sided baking/casserole dish. Set aside.
3. Spoon the apple filling on top and spread into an even layer, all the way out to the edges. Use a knife or bench scraper to cut the apple filling-topped dough into 6 equal-sized pieces. Stack them on top of each other, then use your hands to form it back into a dough ball (this part is messy!). Transfer the dough ball to the prepared Dutch oven. Let sit 30-60 minutes or until the dough has again doubled in size.
4. Preheat the oven to 425 degrees F. Place the lid on the Dutch oven or casserole dish and place in the oven. Bake 30-40 minutes or until the bread is set or until a toothpick inserted into the center comes out clean.

To serve:

1. Transfer the bread to a wire rack and let cool. In a small bowl, whisk together the glaze ingredients. Drizzle on top of the bread. Slice and serve with butter.