In a large mixing bowl, combine warm water, yeast, and honey. If using active dry yeast, let the mixture stand for 5 to 10 minutes until foamy. If using instant yeast, continue directly to the next step.
Add the eggs and oil. Whisk until combined.
Add 3½ cups flour and the salt. Mix until a shaggy dough forms.
Knead with a stand mixer fitted with a dough hook for 6 to 8 minutes, or knead by hand on a lightly floured surface for 8 to 10 minutes. Add the remaining flour only as needed. The dough should be smooth, soft, and slightly tacky.
Shape the dough into a ball and place it in a lightly oiled bowl. Cover and let rise in a warm, draft-free place for 1 to 1½ hours, until doubled in size or noticeably puffy.
While the dough rises, combine the diced apples, brown sugar, cinnamon, flour or cornstarch, and lemon juice, if using. Set aside.
Grease a 9-by-5-inch loaf pan and line it with parchment paper, leaving overhang on the long sides.
Punch down the risen dough. On a lightly floured surface, roll it into a 12-by-16-inch rectangle.
Spread the softened butter evenly over the dough, leaving a small border around the edges. Sprinkle the cinnamon apple filling evenly over the butter.
Cut the dough into 12 equal rectangles or squares. Stack the pieces loosely, then stand the stack upright in the prepared loaf pan so the cut layers face upward.
Cover the pan and let the dough rise again for 30 to 40 minutes, until puffy.
Preheat the oven to 350°F / 175°C. Whisk 1 egg with 1 tablespoon water and gently brush the egg wash over the risen dough.
Bake for 35 to 40 minutes, until deeply golden brown. If the top browns too quickly, tent it loosely with foil during the final 10 minutes of baking.
Remove the bread from the oven and let it cool in the pan for 10 minutes. Use the parchment overhang to lift it out, then cool on a wire rack.
Brush the warm bread with 1 tablespoon honey, if desired. Serve warm or at room temperature.