Prep the pan. Line an 8-inch square baking pan with parchment paper, leaving a slight overhang on two sides for easy lifting.
Lightly grease the parchment.
Toast the pecans. Spread pecans on a sheet pan and toast at 350°F (175°C) for 6–8 minutes until fragrant. Cool slightly, then roughly chop. Toasting deepens flavor and keeps the bars from tasting flat.
Make the crust. In a bowl, mix almond flour, oats, coconut sugar, salt, and cinnamon.
Stir in melted coconut oil (or butter) and vanilla. Add 1–2 tablespoons of cold water only if the mixture looks dry; it should hold together when pinched.
Press and par-bake. Firmly press the crust into the lined pan in an even layer. Use the bottom of a measuring cup to compact it.
Bake at 350°F (175°C) for 12–14 minutes until the edges just turn golden.
Make the filling. In a medium bowl, whisk eggs until smooth. Add maple syrup, coconut sugar, melted fat, vanilla, and salt. Whisk until glossy and well combined.
Stir in the chopped pecans.
Assemble. Pour the filling over the warm crust and spread evenly. Gently tap the pan on the counter to remove air bubbles and level the nuts.
Bake. Return to the oven and bake for 18–22 minutes, until the center is set and no longer jiggles when you nudge the pan. The top should look slightly glossy with toasted pecan edges.
Cool completely. Cool in the pan on a rack for at least 1 hour.
For the cleanest slices, chill for another 30–60 minutes before cutting.
Slice and serve. Use the parchment overhang to lift out the slab. Cut into 16 small bars or 9 larger squares. Serve as is, or with a dollop of Greek yogurt for a creamy contrast.