Rolled Lasagna From Clinton Kelly's Instagram

For the bolognese, heat butter and olive oil on medium heat in a medium sauté pan. Add onion, celery and carrots and cook until onions become translucent, about 7 minutes. Add ground beef, season with salt, pepper and nutmeg. Cook, stirring well and breaking up large chunks, until the meat is cooked through. (It's not necessary for the meat to brown.) Add the milk and simmer until almost all of it has evaporated. (Milk solids will remain.) Add the wine and simmer until almost all of it has evaporated. Stir in the tomatoes and their juices and increase the heat to medium-high. When the tomato juices begin to boil, reduce the heat to very low. Cook, uncovered, at just under a simmer for at least 3 hours, stirring every half hour or so. If the sauce becomes dry, add a little water. After 3 hours, the sauce should be quite thick; season to taste.

For the béchamel, in a medium saucepan, melt butter over medium-high heat. When bubbly, add flour and stir thoroughly to create a roux. Cook until the roux is golden in color, not brown, about 2 minutes. In a slow, steady stream, add the warmed milk, whisking constantly. Add a pinch of salt, a few grindings of black pepper and a pinch of nutmeg. When all the milk has been incorporated, bring the mixture to a boil, then reduce heat to medium and cook on a low boil for 3 minutes. Remove from heat. 

For the red sauce, in a medium saucepan over medium heat, combine the tomatoes and any juices, the butter, onion, a generous pinch of salt and a few grindings of pepper. Simmer for about 45 minutes, stirring occasionally. Discard the onion. Season to taste. 

To assemble the lasagna, preheat oven to 400˚F. 

On a lightly floured work surface, lay out 1 lasagna sheet. Using a spatula or the back of a spoon, spread a layer of béchamel sauce on the sheet, then crumble some of the cold bolognese on top. (If the bolognese has been refrigerated, some of the fat will have separated. It contains a lot of flavor, so do not discard and try to sprinkle it evenly on top.) Sprinkle with mozzarella cheese and parmesan. Carefully roll the sheet into a log, then carefully cut with a knife (a bread knife works best) into slices approximately 2 to 2 ½ inches thick. Repeat with remaining ingredients, reserving some mozzarella.

In an 8-by-12-inch glass baking dish, ladle about ½ cup red sauce evenly across the bottom. Arrange the lasagna rolls on top, cut-sides up, crowding them in, if necessary. Ladle the remaining red sauce into any gaps and over the tops of the rolls. Sprinkle with the reserved lasagna. Tent with foil, then bake until the lasagna rolls in the center of the dish are heated through. (Heating times will vary based on the temperatures of the ingredients.) Remove the foil for the last few minutes for the mozzarella to get lightly browned. If desired, broil while being careful to not let the cheese burn. Serve sprinkled with parsley and more parmigiano-reggiano.