Instructions

1. Make the dough: Pulse together flour and semolina in a food processor. With the motor running, gradually add yolks, olive oil, pinch of salt, and 6–8 tbsp. cold water until dough forms. Transfer dough to a work surface; knead until dough is smooth, about 10 minutes. Form into a ball and wrap in plastic wrap; set aside for 30 minutes.
2. Make the filling: Heat a 6-qt. pan over medium heat. Add spinach and 2 tbsp. water; cook, covered, until wilted, 3–5 minutes. Transfer spinach to a colander and let cool, then squeeze dry; set aside. Melt butter in a 12" skillet over medium-high heat. Cook onion until soft, 2–3 minutes. Add chicken; cook, stirring and breaking up meat into small pieces, until just cooked, about 6 minutes. Add mushrooms and garlic; cook for 3 minutes. Transfer to a food processor with spinach, egg, parmesan, nutmeg, lemon zest and juice, salt, and pepper; purée. Using your hands, divide mixture into 20 balls. Place on a plate; freeze until firm.
3. Make the agnolotti: Roll dough into a 3' x 4' rectangle. With a long side facing you, brush 2 beaten yolks over upper half of dough. Place frozen balls 2" apart over brushed area, leaving a 1" border. Pull lower half of dough over filling; press around balls. Use an inverted drinking glass to cut out each ball. To create the agnolotti shape, pull the glass slightly toward you as you cut. Bring a large pot of salted water to a boil. Working in batches, if necessary, cook agnolotti until tender, 6–8 minutes. Serve with tomato sauce, and garnish with torn basil leaves.