Cheddar and Ham Puff

Preheat the oven to 375°F. 

Butter a 9-inch round cake pan; set aside. 

Put butter and 1 cup water into a deep, medium pot and bring to a boil. 

Remove from heat and stir in flours and salt with a wooden spoon until well combined and mixture forms a thick dough ball, about 30 seconds. 

Add eggs one at a time, beating with an electric mixer after each addition, until dough thickens again and becomes glossy. 

Scrape down the sides of the pot after each addition. 

Beat 1 minute more, then stir in parsley and set aside to let dough rest for 5 minutes.

Spread half of the dough in the prepared pan to cover the bottom, then top with ham and half of the cheese. 

Spread remaining dough over the top, then scatter remaining cheese over dough and bake, without opening the oven, until puffed, set and golden brown, about 50 minutes. 

Set aside to let cool for 10 minutes (puff will sink slightly), then transfer to a plate, cut into wedges and serve.