Mix the flour and salt in a bowl. Mound the flour onto a board (or shallow bowl). Make a well in the center; add the spinach mixture. Using a fork, mix everything together, gradually incorporating the flour as you go.

Finish by hand to form a cohesive dough. Depending on how wet your beet puree is you may need to add more water (1 teaspoon at at time) or flour (1 tablespoon at at time) to a form a cohesive dough.

Cover and let rest for 10 minutes before kneading (I use an upturned bowl for this). The dough will be softer and easier to work with.

Knead the dough for 5-7 minutes. Do this by pushing the dough forward with the heel of your hand while rocking the dough back and forth. The goal is a soft, malleable dough. Poke it when you’re done- it should bounce back.

Shape into a ball, cover tightly with plastic wrap, and rest for 30 minutes at room temperature. The next step is to roll and cut the dough. Divide the dough into 6 or 8 portions. (If you don't have a helper, I suggest dividing the dough into 10 pieces to make working and rolling it easier.)

Working with the first piece (keep remaining pieces covered with plastic wrap), flatten it into a rectangular shape.

Begin by feeding the folded dough through the pasta machine at the widest setting. Fold and roll the dough five times at this setting. Afterward, start thinning the dough by turning the dial to the next narrowest setting (e.g., #2) and rolling it through, ideally with a helper to guide and catch the dough.

Continue rolling without folding, progressively narrowing the settings until the desired thinness is achieved (usually 3–4 settings from the thinnest). If the pasta sheet becomes too long, cut it in half to maintain manageable lengths.

Attach the noodle-cutting attachment and feed the thin sheets through, catching the noodles as they emerge. Repeat the process for all remaining dough pieces.