Prepare. Preheat your oven to 350°F (175°C). Also, prep an 8 x 8-inch baking pan for nonstick. I like to use parchment paper that overhangs on two sides of the pan for easy removal. You can also spray the parchment paper with nonstick.
Crust. In a large mixing bowl, us a whisk to combine together the flour, light brown sugar, baking powder, and salt. When well combined you can add the oil and water and stir the ingredients until a crumbly dough forms and no dry flour remains. Press the ingredients into the bottom of your prepared baking pan and bake for 12–15 minutes, or until the crust is just set and lightly golden around the edges.
Combine. In a heavy-bottomed saucepan, whisk together the light brown sugar and cornstarch until evenly combined.Then add the coconut milk, coconut oil, and maple syrup and continue to whisk until smooth.
Heat. Place the saucepan over medium heat and cook, stirring constantly, until the mixture becomes thickened and translucent (about seven minutes).
Pecans. Remove the pan from the heat and stir in the chopped pecans, vanilla extract, cinnamon, nutmeg, salt, and baking soda until everything is evenly incorporated. Then evenly spread the filling over the warm crust. I like to pour the filling onto the crust and then use the backside of a spoon or an offset spatula to evenly spread the filling over the crust.
Bake. Bake the layered bars for 25–27 minutes, or until the filling is set and no longer appears wet in the center.
Cool. Let the bars cool in the pan for 20 minutes. Using the parchment overhang, carefully lift them from the pan and transfer to a wire rack to cool completely before slicing.