Quarter mushrooms. Coarsely chop roasted red peppers. Mince garlic. Halve baguette. Combine 1 Tbsp. olive oil, garlic, and half the Parmesan (reserve remaining for sauce) in a small bowl. Spread mixture on cut sides of baguette, place on a prepared baking sheet, and set aside to bake in a later step. Rinse sausages and pat dry.

Place mushrooms on other prepared baking sheet and toss with 1 Tbsp. olive oil, 1/2 tsp. salt, and 1/4 tsp. pepper. Spread into a single layer (leave room to add sausages later) and roast 8 minutes. Sausages will join mushrooms on baking sheet in a later step. While mushrooms cook, brown sausages.

Place a medium non-stick pan over medium-high heat. Add 2 tsp. olive oil and sausages to hot pan and cook, turning occasionally, until sausages are browned all over, 5-7 minutes. Remove baking sheet with mushrooms from oven and add sausages. Return sheet to oven and roast until sausages reach a minimum internal temperature of 160 degrees and mushrooms have browned, 12-15 minutes. Wipe pan clean and reserve for sauce step.

While sausages and mushrooms are roasting, add pasta to boiling water and cook until just tender, 9-11 minutes. Drain in colander and return to pot. While pasta boils, place baking sheet with garlic bread in oven and bake until golden brown, about 6-9 minutes. Remove from oven and set aside.

Place evaporated milk in pan used to sear sausages and bring to a boil over medium-high heat. Reduce heat to medium-low, add remaining Parmesan cheese (reserve a pinch for garnish), and cook, stirring constantly, until sauce has thickened enough to coat a spoon, 1-2 minutes. Add pasta, mushrooms, and roasted red peppers to sauce and stir to combine. Taste, and add a pinch of salt and pepper, if desired.

Using tongs or a fork to hold sausages, slice sausages into 1" pieces. Spoon pasta onto a plate or shallow bowl and arrange sliced sausages over pasta. Garnish with remaining Parmesan cheese. Serve garlic bread on the side.