Add the pancetta to a large skillet over medium heat and cook until the fat renders and the pancetta is golden and crispy. Using a slotted spoon, transfer the pancetta to a plate, leaving the rendered fat in the skillet.

Add the zucchini to the skillet and season lightly with salt. Cook, stirring occasionally, until tender and deeply golden around the edges.

Transfer the zucchini, along with the rendered pancetta fat and oil remaining in the skillet, to a blender. Add the basil, Parmigiano, olive oil, a pinch of salt, and black pepper. Blend until completely smooth and creamy. Add another small drizzle of olive oil if needed to help it blend.

Meanwhile, bring a pot of well-salted water to a boil. Cook the gemelli until al dente. Before draining, reserve at least 1 cup of pasta water.

Return the drained pasta to the skillet and turn off the heat. Add the zucchini pesto and a splash of reserved pasta water. Toss until glossy and evenly coated, adding additional pasta water as needed.

Divide between bowls and top with the crispy pancetta, additional Parmigiano, fresh basil, and black pepper.