Preheat your oven to 375°F (190°C). Lightly grease a 9-inch pie dish or a deep 10-inch skillet that’s oven-safe.
Warm a large skillet over medium heat.
Add butter and olive oil. Sauté the onion and celery with a pinch of salt until softened, 4–5 minutes.
Add cauliflower and mushrooms. Cook, stirring often, until the mushrooms release their moisture and the cauliflower is just tender, about 6–8 minutes.
Stir in garlic, thyme, rosemary, and paprika.
Cook until fragrant, 30 seconds.
Add the cooked chicken, broth, heavy cream, cream cheese, and Dijon. Stir until the cream cheese melts and the mixture looks smooth and creamy, 3–4 minutes.
If you want a thicker filling, sprinkle in the xanthan gum a little at a time, whisking well to prevent clumps. Simmer 2 minutes until the sauce lightly thickens.
Season with salt and pepper.
Transfer the filling to your pie dish if it’s not already in an oven-safe skillet. Smooth the top.
Make the crust: In a bowl, whisk almond flour, Parmesan, baking powder, garlic powder, salt, and pepper. In another bowl, whisk eggs, melted butter, and sour cream until smooth.
Fold wet into dry until a soft, spreadable dough forms.
Spoon the crust mixture over the filling in small mounds. Gently spread with a spatula to cover, leaving a few small vents. It doesn’t need to be perfect—rustic is fine.
Bake 22–28 minutes, until the crust is set and golden.
If edges brown too fast, tent loosely with foil.
Let the pot pie rest 10 minutes before serving. Garnish with parsley if you like.