Preheat your oven to 350°F (175°C). Spread the chopped pecans evenly on a baking sheet and toast them for about 8-10 minutes, stirring halfway through. Remove and set aside to cool.
In a large bowl, cream together the softened unsalted butter and granulated sugar using an electric mixer on medium speed until light and fluffy, about 4-5 minutes.
Add the eggs one at a time, beating well after each addition. Stir in the vanilla extract.
In a separate bowl, whisk together the all-purpose flour, baking powder, and salt to combine evenly.
Reduce mixer speed to low. Add the dry ingredients to the butter mixture in three parts, alternating with the buttermilk in two parts, starting and ending with dry ingredients. Mix just until combined after each addition.
Gently fold the toasted pecans into the batter using a spatula, distributing evenly without deflating.
Grease and flour a 9x5-inch loaf pan. Pour the batter into the pan and smooth the top. Bake for 60-70 minutes or until a toothpick inserted in the center comes out clean. Check after 50 minutes to avoid overbaking.
While the cake bakes, whisk together the powdered sugar and maple syrup in a small bowl until smooth. Add a teaspoon of water if glaze is too thick.
Remove cake from oven and allow it to cool in the pan for 15 minutes. Transfer to a wire rack over a baking sheet. While still warm, drizzle the maple glaze over the cake, letting it seep down the sides.