Egg Noodle, Chard, and Fontina Torte

Put oven rack in middle position and preheat oven to 375°F. Grease pan with 2 teaspoons oil and wrap outside with foil.
Cook chard in a 5- to 6-quart pot of boiling salted water, uncovered, until just tender, about 3 minutes. Transfer with a slotted spoon to a sieve set over a bowl. Reserve cooking water in pot. Press hard on chard to extract as much water as possible, then transfer to a cutting board and chop.
Cook onion in 3 tablespoons oil in a 12-inch heavy skillet over moderate heat, stirring occasionally, until softened and golden brown, about 15 minutes. Add garlic and cook, stirring, 1 minute. Stir in chard, 1/2 teaspoon salt, and 1/4 teaspoon pepper and remove from heat. Cool chard mixture to warm.
While chard cools, return cooking water to a boil and cook fettuccine, uncovered, until al dente. Drain pasta in a colander, then transfer to a large bowl and toss with remaining teaspoon oil. Blend together eggs, milk, mascarpone, and remaining 3/4 teaspoon salt and 1/4 teaspoon pepper in a blender until smooth.
Stir chard and Fontina into pasta mixture, then stir in egg mixture. Pour into greased springform pan set in a large shallow baking pan (to catch any drips). Pat down chard to make surface even if necessary.
Bake until just set and top is golden brown, 50 minutes to 1 hour. Cool in springform pan on a rack 10 minutes, then run a small sharp knife around inside edge of pan to loosen torte. Remove side of pan and serve torte hot or warm.