Adjust rack to top position (top and middle positions for 4 servings) and heat broiler to high. Place cream cheese in a small bowl of warm water to soften. Wash and dry produce.

Trim and quarter mushrooms (skip if your mushrooms are pre-sliced!). Trim and halve zucchini lengthwise; cut crosswise into ¼-inch-thick half-moons.

Heat a large drizzle of oil in a large pan over medium-high heat. Add mushrooms; cook, stirring occasionally, 4 minutes.

Add zucchini, garlic powder, a pinch of salt, and pepper; cook, stirring occasionally, until veggies are lightly browned and tender, 2-3 minutes more.

While veggies cook, finely chop chives. Thinly slice tomato into rounds; season with salt and pepper. Quarter lemon.

In a second small bowl, whisk together softened cream cheese and half the chives until smooth.

Place flatbreads smooth side up on a lightly oiled, foil-lined baking sheet. Toast on top rack until golden brown, 1-2 minutes. (For 4 servings, divide between two lightly oiled, foil-lined sheets; toast on top and middle racks.)

Once flatbreads are toasted, remove sheet from oven. Carefully flip flatbreads, then evenly spread with chive cream cheese. Top with cooked veggies and tomato; sprinkle with Italian cheese blend.

Return to top rack and broil until edges are browned and cheese melts, 2-4 minutes. (For 4 servings, broil on top and middle racks, swapping positions halfway through.) TIP: Watch carefully to avoid burning!

Transfer flatbreads to a cutting board and slice into quarters.

Divide flatbreads between plates. Garnish with remaining chives and a squeeze of lemon juice. Serve with remaining lemon wedges on the side.