Preheat your oven to 350°F (175°C). Line a 9×5-inch loaf pan with parchment paper, leaving some overhang for easy removal.
Peel, core, and dice the apples into 1/4-inch pieces. Toss the diced apples with 1 tablespoon of flour to prevent them from sinking during baking.
In a medium bowl, whisk together the flour, baking powder, baking soda, salt, cinnamon, and nutmeg.
In a large bowl, beat the softened butter and brown sugar until light and fluffy, about 3-4 minutes.
Add eggs one at a time, beating well after each addition. Stir in the vanilla extract and Greek yogurt until smooth.
Gently fold the dry ingredients into the wet mixture until just combined. Do not overmix.
Fold in the diced apples and nuts (if using).
Pour the batter into your prepared loaf pan and smooth the top. Bake for 55-60 minutes, or until a toothpick inserted in the center comes out with a few moist crumbs. If the top starts browning too quickly, loosely cover with foil after 40 minutes.
While the bread is cooling, make the glaze. In a medium saucepan over medium heat, melt the sugar, stirring constantly until it turns amber (about 5 minutes).
Add the butter (be careful, it will bubble vigorously) and whisk until incorporated.
Remove from heat, slowly add the cream while whisking, then stir in the sea salt.
Allow the bread to cool in the pan for 15 minutes, then use the parchment overhang to lift it out onto a wire rack. Let cool for an additional 30 minutes before drizzling with the salted caramel glaze.