Butter a cake pan (7 inches round and 4 inches height), line the bottom with wax paper and butter the wax paper. I didn't have a cake pan with these dimensions so I used a stainless steel saucepan of a similar size.
Preheat your oven to 375°F.
Pour the pumpkin purée in a large bowl. In a small saucepan, heat the milk, butter and sugar on low heat, stirring constantly until the butter has melted. Pour the milk mixture to the pumpkin. Add the cornmeal ½ cup at a time, stirring to blend thoroughly. Stir in the salt.
Add the egg yolks to the pumpkin mixture and blend thoroughly using a spatula. Stir in the rum if using. In a separate mixing bowl, beat the egg whites with a hand mixer until stiff. Fold the egg whites into the batter.
Pour the batter into the prepared pan. Bake on the middle shelf of your oven for about an hour, or when a knife inserted in the center comes out clean. If your knife comes out wet, bake for another 10 minutes.
Allow to cool for 20 minutes before unmolding. Slice into thin servings and serve warm.
Recipe by Lemons + Anchovies at https://lemonsandanchovies.com/2012/11/basque-pumpkin-cornbread/