Preheat your oven to 325°F (163°C). Line a 9×9‑inch pan with parchment paper, and spray lightly with non-stick cooking spray for easy removal.

Melt your butter, allow it to cool a little so it’s warm but not piping hot. Warm the milk until it’s lukewarm (test by touching—it should feel gentle on your skin). Set aside.

In a clean bowl, whip the egg whites with the cream of tartar until they reach stiff peaks. Set aside.

In another bowl, beat the egg yolks with the powdered sugar until the mixture turns pale yellow and lighter in texture.

To the yolk‑sugar mix, add the melted butter, vanilla, cinnamon, ginger, and nutmeg. Mix until just combined.

Add the flour next, mixing gently until incorporated. Then add the pumpkin puree and ½ cup of the milk. Scrape down the sides of the bowl and mix until smooth.

With the mixer set to its lowest speed, gradually add the remaining milk until fully combined into the batter.

Gently fold in the whipped egg whites by hand—use a spatula or large spoon, lifting from the bottom so you keep as much air as possible.

Pour the combined batter into your prepared 9×9 pan. Smooth top if needed.

Bake for 55‑65 minutes. The cake will still be jiggly in the center (that’s good—custard texture), but shouldn’t be runny or liquid.

After baking, let the cake cool down fully before slicing to ensure clean cuts and proper setting.

When serving, optionally sprinkle with powdered sugar and add whipped topping. Some like to warm up a piece in the microwave briefly, then top with whipped cream.