Preheat oven to 350°F. Butter a 9x5x3 inch non stick loaf pan or spry with baking spray. Set aside.
In a medium size mixing bowl, use a whisk to sift together flour, baking powder, baking soda, apple pie spice and salt.
In a separate bowl, use a whisk or an electric mixer to beat together buttermilk, sugar, eggs and vanilla. Add to dry ingredients beating until fully combined.
Add apples and 1 cup pecans to batter. Mix well, pour into prepared pan. Top with remaining ½ cup pecans, pressing gently into batter.
Bake for 55-65 minutes or until a toothpick inserted into the center comes back clean. Check halfway through and lay foil on top, if needed to prevent over browning. Cool in the pan on a cooling rack for 20 minutes.
Meanwhile, in a small saucepan melt together butter and brown sugar. Cook gently on medium for 1-2 minutes until thickened.
Remove loaf from pan and drizzle with glaze. Cool completely.
Store in an airtight container at room temperature for up to 3 days.