Instructions

1. Position rack in lower third of oven and preheat to 400F.Butter 6-cup (1 1/2-quart) soufflé dish. Add Parmesan cheese and tilt dish, coating bottom and sides. Warm milk in heavy small saucepan over medium-low heat until steaming. Meanwhile, melt butter in heavy large saucepan over medium heat. Add flour and whisk until mixture begins to foam and loses raw taste, about 3 minutes (do not allow mixture to brown). Remove saucepan from heat; let stand 1 minute. Pour in warm milk, whisking until smooth. Return to heat and cook, whisking constantly until very thick, 2 to 3 minutes. Remove from heat; whisk in paprika, salt, and nutmeg. Add egg yolks 1 at a time, whisking to blend after each addition. Scrape soufflé base into large bowl. Cool to lukewarm. DO AHEAD: Can be made 2 hours ahead. Cover and let stand at room temperature. Using electric mixer, beat egg whites in another large bowl until stiff but not dry. Fold 1/4 of whites into lukewarm or room temperature soufflé base to lighten. Fold in remaining whites in 2 additions while gradually sprinkling in Gruyère cheese. Transfer batter to prepared dish. Place dish in oven and immediately reduce oven temperature to 375F. Bake until soufflé is puffed and golden brown on top and center moves only slightly when dish is shaken gently, about 25 minutes (do not open oven door during first 20 minutes). Serve immediately.
2. Butter 3 1-cup (6-7oz) soufflé dishes (fingers work wonders). Sprinkle Parmesan cheese into dish, tilting to coat bottom and sides.
3. Warm milk in heavy small saucepan over medium-low heat until steaming.
4. Meanwhile, melt butter in heavy large saucepan over medium heat. Add flour and whisk constantly until mixture begins to foam and loses raw taste (the taste of flour), about 3 minutes. Do not allow mixture to brown!
5. This is a roux, and the start of a white Béchamel sauce.
6. Remove saucepan from heat, let stand 1 minute. Pour in warm milk, whisking until smooth. Return to heat and cook, whisking constantly until very thick, 2 to 3 minutes.
7. Remove from heat and whisk in paprika, salt, and nutmeg. Add egg yolks 1 at a time, whisking to blend after each addition.
8. Scrape soufflé base into a large mixing bowl. Cool to lukewarm, cover and let stand at room temperature.
9. Position rack in lower third of oven and preheat to 400F.
10. Using electric mixer, beat egg whites in another large bowl with cream of tartar until stiff but not dry. Start the mixer on slow and gradually get to top speed (this will help keep the bubbles small and consistent).
11. Gently fold 1/3 of whites into lukewarm or room temperature soufflé base. Fold in remaining whites in 2 additions with 1/2 of Gruyère cheese each addition.
12. Transfer batter to prepared soufflé dishes, filling no dish higher than about 2/3 full.
13. Place dishes in oven and immediately reduce oven temperature to 375F. Bake until soufflé is puffed and golden brown on top and center moves only slightly when dish is shaken gently, about 22 minutes (do not open oven door during first 20 minutes). If you poke it to test, it'll start deflating before you remove it from the oven.
14. Serve immediately.