Prep the pan and oven: Heat the oven to 350°F (175°C).
Line an 8x8-inch baking pan with parchment, leaving overhang on two sides for easy lifting. Lightly grease the parchment.
Make the crust: In a bowl, stir together the oats, almond flour, brown sugar, cinnamon, and salt. Add melted coconut oil, maple syrup, and vanilla.
Mix until the oats look evenly moistened and clump together.
Press and par-bake: Firmly press the crust mixture into the prepared pan in an even layer. Use the bottom of a measuring cup to compress. Bake for 10 minutes to set.
Mix the filling: In a separate bowl, whisk pumpkin puree, Greek yogurt, eggs, maple syrup, brown sugar, protein powder, spices, vanilla, and salt until smooth.
If your protein powder clumps, sift it first or whisk thoroughly.
Assemble: Pour the filling over the warm crust. Tap the pan gently on the counter to release air bubbles and smooth the top with a spatula.
Bake: Return to the oven and bake for 28–35 minutes, until the edges are set and the center has a slight wobble. The surface may puff a bit and then settle as it cools.
Cool completely: Place the pan on a rack and let it cool to room temperature.
Then refrigerate for at least 2 hours to set. This helps the bars slice cleanly.
Slice and serve: Use the parchment overhang to lift the slab out. Cut into 9–12 bars.
Top with a spoonful of yogurt or a dusting of cinnamon if you like.