1. 1. Preheat your oven to 325°F. Grease and flour a 9×13-inch baking dish.

2. 2. In a saucepan, melt the butter over medium heat. Add the milk and warm it until just simmering, then remove from heat.

3. 3. In a large bowl, whisk the egg yolks with 1 cup of confectioners’ sugar, vanilla extract, cinnamon, pumpkin pie spice, and pumpkin puree until smooth and well combined.

4. 4. Slowly pour the warm milk mixture into the yolk mixture, whisking constantly. Stir in the flour until the batter is fully incorporated and smooth.

5. 5. In a separate clean bowl, beat the egg whites with a pinch of cream of tartar until soft peaks form. Gradually add the remaining 1/2 cup of confectioners’ sugar and continue beating until stiff peaks form.

6. 6. Gently fold the whipped egg whites into the pumpkin batter, being careful not to deflate them.

7. 7. Pour the batter into the prepared baking dish and bake for 50–60 minutes, or until the top is golden brown and a toothpick inserted into the center comes out clean.

8. 8. Allow the cake to cool completely before slicing.