Fill a medium pot (or large for 4 servings) 3/4 of the way up with salted water; cover and heat to boiling on high. Wash and dry the fresh produce. Thinly slice the scallions, separating the white bottoms and hollow green tops. Remove any husks and silks from the corn; cut the kernels off the cobs. Cut off and discard the stem of the pepper(s). Halve lengthwise; remove the ribs and seeds, then medium dice. Roughly chop the pistachios.

Meanwhile, add the pasta to the pot of boiling water. Cook, stirring occasionally, 8 to 10 minutes, or until tender. Turn off the heat. Reserving ½ cup of the pasta cooking water (or 1 cup for 4 servings), drain thoroughly and return to the pot.

In a medium nonstick pan (or large for 4 servings), heat a drizzle of olive oil on medium-high until hot. Add the pancetta. Cook, stirring occasionally, 4 to 5 minutes, or until lightly browned and cooked through. Leaving any browned bits (or fond) in the pan, transfer to a paper towel-lined plate.

In the pan of reserved fond, heat a drizzle of olive oil on medium-high until hot. Add the sliced white bottoms of the scallions. Cook, stirring constantly, 30 seconds to 1 minute, or until softened. Add the corn kernels and diced pepper(s); season with salt and pepper. Cook, stirring occasionally, 3 to 5 minutes, or until lightly browned and softened. Turn off the heat.

To the pot of cooked pasta, add the cooked vegetables, cooked pancetta, red pepper pesto, half the reserved pasta water, and as much of the chile paste as you'd like, depending on how spicy you'd like the dish to be. Cook on medium-high, stirring frequently, 1 to 2 minutes, or until combined and the pasta is coated (if necessary, gradually add the remaining cooking water to ensure the pasta is thoroughly coated). Turn off the heat. Add the mascarpone; stir until combined. Serve the finished pasta garnished with the sliced green tops of the scallions, parmesan, and chopped pistachios.