(about 1 lb.)
Salt and freshly ground black pepper, to taste
3 tbsp. vegetable oil
1 large head broccoli (about 2 lbs.), stemmed and
broken into 1"–2" florets
5 tbsp. butter
1⁄4 cup flour
1 cup Chicken Stock
1 cup milk
3 tbsp. sherry
1⁄8 tsp. freshly grated nutmeg
1⁄2 cup finely grated parmigiano-reggiano
1 cup slivered almonds
1⁄2 cup heavy cream
1. Season chicken with salt and pepper. Heat oil in a large skillet over medium heat. Add chicken and cook, turning once, until golden brown and just cooked through, 13–15 minutes. Transfer chicken to a plate; let cool slightly. Cut chicken lengthwise on the bias into 1⁄4"-thick slices and set aside.
2. Meanwhile, put broccoli into a large pot, cover with salted water, and bring to a boil over medium-high heat. Reduce heat to medium-low and simmer until barely tender, 2–3 minutes. Drain and set aside.
3. Preheat oven to 375°. Rub the inside of a 2-quart casserole dish with 1 tbsp. of the butter; set aside. Melt remaining 4 tbsp. butter in a saucepan over medium heat. Add flour and cook, stirring, for 1 minute. Gradually pour in stock and milk while whisking constantly. Cook until very thick, about 10 minutes. Add salt and pepper, sherry, nutmeg, and 1⁄4 cup of the cheese; stir until cheese melts, about 1 minute. Remove cheese sauce from heat and let cool slightly.
4. Arrange broccoli in the prepared dish in a single layer; sprinkle with remaining 1⁄4 cup cheese. Arrange chicken evenly over top; sprinkle with almonds. In a large bowl, beat the heavy cream to soft peaks; fold into sauce. Pour sauce over chicken. Bake, with a baking sheet underneath to catch any drips, until golden brown and bubbling, about 30 minutes.