Step 1

Combine 1/2 cup hot water and porcini mushrooms in a bowl; let stand 20 minutes. Drain mushrooms in a colander over a bowl; reserve soaking liquid. Finely chop porcini mushrooms.

Step 2

Place 1 squash half, cut side down, in an 8-inch square glass baking dish. Add water to a depth of 1 inch. Cover and microwave at HIGH 8 minutes or until tender when pierced with a fork. Remove squash half; cool. Repeat procedure with remaining squash half.

Step 3

Heat oil in a large Dutch oven over medium-high. Add onion and next 7 ingredients (through button mushrooms); cook 12 minutes, stirring occasionally. Stir in tomato paste; cook 2 minutes. Stir in reserved porcini mushrooms, reserved soaking liquid, soy sauce, and next 4 ingredients (through tomatoes); reduce heat and simmer 10 minutes.

Step 4

Scrape inside of squash halves with a fork to remove spaghetti-like strands. Divide squash among 4 plates; top evenly with mushroom mixture and cheese.