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1
To make Tomato Sauce: In medium saucepan, heat oil over medium heat.
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2
Cook onion and garlic for about 3 minutes.
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3
Add next 7 ingredients (up to, but not including, tomatoes) and cook for about 8 minutes or until liquid has evaporated.
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4
Stir in tomatoes, peppers, paste and vinegar.
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5
Heat to boiling, reduce temperature and, stirring often, simmer for about 1 hour or until thick enough to mound on a wooden spoon.
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6
In large pot of boiling water, cook lasagna noodles for about 8 minutes or until tender.
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7
Drain (reserving hot water) and rinse under cold water.
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8
Set aside.
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9
Stir spinach into hot water and cook for 1 minute.
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10
Drain and squeeze out liquid.
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11
Chop coarsely.
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12
To make White Sauce: Melt butter in medium saucepan, gradually whisk in flour and over medium heat cook, stirring constantly, for about 3 minutes.
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13
Remove pan from heat and whisk in milk, salt, pepper and nutmeg.
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14
Cook over medium heat, stirring constantly, until thickened (10-15 minutes).
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15
Whisk in 1/2 cup Asiago and 1/3 cup Parmesan cheeses until melted.
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16
To Assemble: Spread 1/4 of the tomato sauce in a 9 by 11 inch baking dish.
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17
Top with single layer of noodles, trimming to fit dish.
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18
Repeat layering (tomato sauce/noodles).
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19
Spread with 1/3 white sauce, and a single layer of noodles.
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20
Top with all of the spinach and the remaining Asiago cheese.
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21
Top with single layer of noodles, 1/4 tomato sauce, noodles and 1/3 white sauce.
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22
Repeat layering (noodles/tomato sauce/noodles/white sauce).
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23
Cover with aluminum foil.
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24
Lasagna can be refrigerated at this point and cooked the next day (add 10 minutes to first baking time).
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25
Place dish on baking sheet and cook in a 375F (190C) degree oven for 30 minutes.
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26
Remove from oven and sprinkle with remaining Parmesan cheese.
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27
Return to oven and bake, uncovered, for another 30 minutes or until cheese is golden.
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28
Let stand for 20 minutes before serving.
