Preheat your oven to 175°C (350°F). Line a 9-inch square baking pan with parchment paper, leaving overhang on the sides for easy removal.
In a mixing bowl, combine the all-purpose flour, brown sugar, and salt. Stir until evenly mixed.
Add the melted butter to the dry ingredients and mix with a spatula or spoon until the mixture resembles coarse crumbs that hold together when pressed.
Press the crumbly mixture evenly into the prepared pan, using the back of a spoon or your fingers to create a smooth, compact layer.
Bake the crust for about 15 minutes, or until it turns golden around the edges and smells fragrant.
While the crust bakes, chop the pecans roughly and toast them in a dry skillet over medium heat for about 3-4 minutes, stirring frequently until fragrant and slightly darker. Remove from heat and set aside.
In a saucepan over medium heat, pour in the maple syrup and bring to a gentle simmer, bubbling softly and filling the kitchen with a warm caramel aroma.
Stir in the vanilla extract and continue simmering for another 2-3 minutes, then remove from heat.
Spread the toasted pecans evenly over the hot crust, then pour the warm maple mixture over the pecans, gently spreading to cover the entire surface.
Return the pan to the oven and bake for an additional 20-25 minutes, until the filling is bubbling around the edges and the pecans on top look toasted and shiny.
Remove from the oven and let the bars cool completely in the pan on a wire rack for about 2 hours, allowing the filling to set firmly.
Once cooled, lift the bars out of the pan using the parchment overhang. Use a sharp knife to cut into 12 squares, wiping the blade clean between cuts for neat edges.
Serve the bars at room temperature or slightly warmed, and enjoy the crunchy, gooey layers with their irresistible maple and nut aroma.
