Heat milk/water until it is just warm (100 - 100 F). Take 1/4 C water and dissolve 1 tbsp sugar in it. Sprinkle the yeast on top and set aside for 5 to 10 minutes until the yeast becomes bubbly.

Mix the 1 1/2 ap flour, ww flour, sugar, and salt in a large bowl. Coarsely grate the apple. Make a well at the center of the flour mix, and add the yeast mixture, followed by the egg, grated apples, and the activated yeast mix. Knead to form a soft dough adding the remaining liquid, one tablespoon at a time.

If using a machine knead for up to 4 minutes using the dough hook. If the dough seems very tacky add the remaining flour.

Follow the same process if kneading by hand. Once the dough has come together it takes about 10 minutes of kneading by hand. Add the remaining flour if the dough sticks to the hand while kneading.

Oil a medium bowl and transfer the dough ball into it. Turn the dough so that all sides are evenly coated in oil. Cover with a wet kitchen towel or plastic wrap and let rise in a warm place till doubled - about 1 hour.

Chop the walnuts coarsely. Soften 3 tablespoons of unsalted butter. Mix the brown sugar and cinnamon well.

Coat the insides of a 9 X 5 loaf pan with butter. Punch down the dough. Lightly flour a kneading surface. Roll out the dough into a 10-inch X 12-inch rectangle. Spread the softened butter on the dough rectangle.

Sprinkle the cinnamon sugar and the chopped walnuts on top. Fold the dough along the short edge to create a 5X 12 rectangle. Cut into 8 equal pieces. Arrange the pieces side by side in the loaf pan with the ends facing up. If there is any leftover filling, sprinkle it on the top. Cover with a plastic wrap and let rise in a warm place till almost doubled about 30 to 45 minutes.

Preheat the oven to 350 °F (175 °C) and bake for 30 to 40 minutes until done (Refer to notes). Cool in the pan for 5 minutes. Transfer to a wire rack and cool completely.

Whisk together powdered sugar, milk, and vanilla. Drizzle over the cooled bread.