Preheat the oven to 350°F (175°C). Lightly grease a 9x13-inch baking pan with nonstick spray. In a mixing bowl, combine the almond flour, baking powder, and a pinch of salt. Add the eggs, butter, water, and heavy cream. Stir until smooth and pour the batter into the prepared pan. Bake for 15–20 minutes, or until a knife inserted into the center comes out clean. Set aside to cool before crumbling into pieces.

In a skillet over medium heat, melt the butter. Add the onion and celery and cook until softened and lightly browned. Pour in ½ cup of bone broth and continue cooking until the vegetables are tender and the broth has mostly evaporated. Remove from heat and set aside.

In the same skillet, melt 1 tablespoon of butter. Add the sage leaves and sauté briefly, 20–30 seconds, until aromatic. Remove from heat.

In a large bowl, beat the eggs and mix in the toasted sage. Add the crumbled cornbread, sautéed vegetables, poultry seasoning, and additional salt and pepper, if desired. Gradually stir in 1 cup of bone broth, ensuring the mixture is moistened but not soggy.

Preheat the oven to 375°F (190°C) and lightly grease a 9x13-inch baking dish. Transfer the stuffing mixture into the pan, spreading evenly. Bake for 20 minutes, or until the top is lightly golden. Remove from the oven, allow to rest briefly, and serve warm.