1. Fit your pasta extruder or stand-mixer attachment with the chilled bucatini plate. If using a pasta extruder, set it to medium speed. If using a stand mixer, with the machine running on medium speed, feed the dough into the hopper in marble-size clumps, using a pushing tool to push the clumps into the auger, being careful not to overload it. As the pasta is extruded, cut it into 9-inch (23-cm) lengths and immediately dust it with semolina to prevent sticking. (If you don’t have time to make fresh pasta, use dried bucatini for this recipe).
2. Dry the pasta by placing it on wire racks that will fit in your refrigerator and refrigerate it uncovered for at least 8 hours or up to 4 days. The pasta will get drier and harder as it sits. I like the texture after 2 days in the refrigerator.
3. Toast the almonds in a large, deep sauté pan over medium heat, shaking the pan now and then, until they are fragrant, 3 to 4 minutes. Transfer 1 cup (145 g) of the almonds to a blender or food processor. Chop the remaining ¼ cup (36 g) almonds with a knife and set them aside. Add 1 clove garlic and ¼ cup (60 ml) of the oil to the blender or processor. Turn on the machine and drizzle in another ¼ cup (60 ml) of the oil, blending until the pesto is relatively smooth. Taste the pesto, adding salt until it tastes good to you.
4. Bring a large pot of salted water to a boil. Drop in the bucatini, cover the pot to quickly return the water to a boil, and cook the pasta until it is tender but still a little chewy when bitten, 4 to 5 minutes (8 to 10 minutes for fully dried boxed pasta). Drain the pasta and reserve the pasta water.
5. Meanwhile, heat the remaining 1 tablespoon oil over medium heat in the pan used to toast the almonds. Thinly slice the remaining garlic clove and add it to the pan along with the jalapeño. Cook, stirring occasionally, until the garlic is golden brown, 4 to 5 minutes.
6. Add 1 cup (237 ml) of the pasta water to the pan, swirling the water and scraping up any browned bits on the pan bottom. Add the drained pasta and the almond pesto and toss until the sauce reduces slightly, gets creamy, and coats the pasta, about 1 minute. Remove the pan from the heat and add 1/2 cup (50 g) of the Parmesan. Keep the pasta moving until the cheese melts and pasta and sauce become one thing in the pan. Taste it, adding salt until it tastes good to you.
7. Dish out the pasta onto warmed plates and garnish with the remaining 1/2 cup (50 g) Parmesan and the reserved almonds.