Bread

• 1/2 cup unsalted butter to be browned
• 2/3 cup (130) granulated or cane sugar
• 2 large eggs, at room temperature
• 2 tsp vanilla extract
• 1/4 cup (60ml)  milk
• 1/2 cup (120g) sour cream
• 1 3/4 cups + 2 TBSP (225g) all-purpose flour
• 1 1/2 tsp baking powder
• 1/2 tsp baking soda
• 1/2 tsp salt

Apple Layer

• 2 medium apples (about 2 cups or 240 g), peeled, cored and diced into small cubes. I used honey crisp.
• 2 TBSP Butter
• 2 TBSP  brown sugar
• 1 tsp ground cinnamon
• 1 tsp lemon juice or 1/2 tsp apple cider vinegar
• 1 TBSP all purpose flour

Cinnamon Sugar

• 1/3 cup  brown sugar
• 2 tsp ground cinnamon
• pinch of salt
• pinch of ground cardamon (optional)

Glaze

• 1/2 cup (60g) powdered sugar
• 1 TBSP  milk or cream
• 1/2 tsp vanilla extract
• pinch of salt

1. Brown the butter(8see notes below):  In a light-colored saucepan, melt ½ cup (113g) unsalted butter over medium heat. Stir often as it foams, sizzles, and then quiets. Cook until golden brown specks form on the bottom and the butter smells nutty. Remove from heat and pour into a heatproof bowl to cool for 10 minutes.
2. Prepare the apple filling: In the same skillet used to brown butter, melt 2 Tbsp butter over medium heat. Add diced apples, brown sugar, cinnamon, and lemon juice (or vinegar). Cook 3–4 minutes, until just softened. Remove from heat, stir in 1 Tbsp flour, and set aside to cool slightly.
3. Mix the cinnamon sugar: In a small bowl, combine brown sugar, cinnamon, salt, and cardamom (if using).
4. Make the batter:  Preheat oven to 350°F (177°C). In a large bowl, whisk cooled browned butter with granulated sugar until combined. Add eggs one at a time, whisking well. Stir in vanilla, milk, and sour cream until smooth. In another bowl, whisk together flour, baking powder, baking soda, and salt. Gently fold dry ingredients into wet ingredients until just combined. Do not overmix.
5. Assemble the loaf:  Spread half the batter into a greased and lined 9×5-inch loaf pan. Spoon half the apple mixture over the batter, try to keep the apples in the center of the batter and away from the edges, then sprinkle half the cinnamon sugar mixture. Repeat layers with remaining batter, then apples, and top the loaf off with cinnamon sugar.
6. Bake: Bake at 350°F (177°C) for 50–60 minutes, or until a toothpick inserted in the center comes out mostly clean (a few moist crumbs are okay). If the top browns too quickly, cover loosely with foil for the last 15 minutes.
7. Cool & glaze: Let loaf cool in pan for 15 minutes, then transfer to a wire rack. Whisk powdered sugar, milk, vanilla, and salt until smooth. Drizzle over cooled loaf. Slice and enjoy

Notes:

*How to Brown Butter (Step by Step)

1. Place the butter in a light-colored saucepan (so you can see the color change).
2. Melt over medium heat, stirring with a silicone spatula.
3. The butter will foam, then sizzle, and finally quiet down.
4. Watch closely—milk solids will sink and turn golden brown. You’ll smell a nutty, toffee-like aroma.
5. Remove from heat immediately and pour into a heatproof bowl to stop cooking.

Tip: Don’t walk away—brown butter can go from perfect to burnt in seconds.

Tips for Success

• Cut apples small (¼-inch cubes) so they soften evenly without sinking.
• Layer, don’t stir – Keep apple mixture and cinnamon sugar layered in the batter, not mixed in, for that swirled fritter effect.
• Room-temperature eggs help the batter emulsify for a smooth texture.
• Don’t overmix – Stir just until the flour disappears. Overmixing = tough bread.
• Cool before glazing – Let the loaf rest at least 20 minutes, or the glaze will melt off.