Method

• 1.
  For spaghetti, bring a saucepan half-filled with water to the boil. Add spinach and blanch for 20-30 seconds until just wilted. Refresh in iced water, then place in a clean tea towel. Squeeze out as much water as possible. Pulse spinach and egg in a blender until spinach is very finely chopped.
• 2.
  Place flour, semolina, parsley, 1 tsp fine salt and oil in a stand mixer fitted with the dough hook. Make a well in the centre. Add spinach and egg mixture and mix on low speed. Increase speed to medium and knead for 5-6 minutes until smooth and elastic. You may need to add a little more flour, 1 tsp at a time, if the dough looks a little wet. Enclose in plastic wrap and rest for 1 hour at room temperature.
• 3.
  Divide dough into 4 equal pieces and, working with a piece at a time (enclose remaining in plastic), start on thickest setting of pasta machine and run dough through 2-3 times, folding it in half each time, until elastic. Keep rolling, reducing settings notch by notch, until 2mm thick. Place pasta on a semolina-dusted tray and cover with a clean tea towel while you roll remaining pieces.
• 4.
  Cut pasta into strands using a thick spaghetti attachment and spread on a semolina-dusted tray. Set aside to dry for at least 30 minutes before using.
• 5.
  Bring a large saucepan three-quarters full with boiling salted water to the boil. Add spaghetti and cook, stirring frequently, for 2-3 minutes until just cooked. Drain, reserving 1 cup (250ml) pasta water, and place in a large heatproof bowl.
• 6.
  Working quickly, heat a large, deep non-stick frying pan over high heat. Add butter, black pepper, cheeses and reserved pasta water and cook, swirling pan, for 2-3 minutes until cheeses have melted. Add pasta and toss well to combine. If pasta looks too dry, add a little more water. Season to taste and divide among bowls. Scatter with freshly ground black pepper and extra grana padano to serve.