Preheat and prep pan: Preheat the oven to 350°F and line an 8x8-inch baking pan with parchment paper, leaving an overhang on two sides for easy lifting later.
Whisk dry ingredients: In a medium bowl, whisk together the flour, baking powder, cinnamon and salt until evenly combined.
Mix butter and sugar: In a large bowl, stir the melted butter and brown sugar together until smooth and glossy.
Add egg and vanilla: Whisk in the egg and vanilla extract until the mixture looks thick and well blended.
Combine wet and dry: Add the dry ingredients to the wet mixture and stir just until no streaks of flour remain; the batter will be thick.
Fold in apples and pecans: Gently fold the diced apples and chopped pecans into the batter so they are evenly distributed.
Spread first layer: Press about half of the batter into the bottom of the prepared pan in an even layer.
Scatter the caramel: Distribute the halved caramel candies evenly over the batter, leaving a small border around the edges.
Top with remaining batter: Dollop the rest of the batter over the caramel and spread gently with a spatula to cover it completely.
Bake until golden: Bake for 30 to 35 minutes, until the top is golden brown and the edges pull slightly away from the sides of the pan.
Cool completely: Let the pan cool at room temperature for at least 1 hour so the caramel firms up before cutting.
Slice into bites: Lift the slab out using the parchment overhang, sprinkle with flaky sea salt, and cut into 1-inch squares.