Slice each Zucchini in half lengthways. Using a vegetable peeler, peel ribbons to the centre of the Zucchini; flip and peel again. Discard centre core or chop finely to add to the sauce.
Heat a skillet over medium heat. Add the bacon (or Pancetta) and sauté until golden and crisp (about 5 minutes).
While the bacon is frying; whisk the eggs, cream and cheeses together until well-combined.
Add the Zucchini ribbons to the pan, and continue to sauté with the bacon until just starting to soften. Reduce heat down to low (very important), and slowly pour in the the egg mixture while stirring quickly until the sauce thickens. The residual heat will cook the eggs but work quickly to prevent the eggs from scrambling.
Season with freshly cracked black pepper, add salt to your taste (if using); divide the 'Zettuccini' into bowls and serve immediately.
Notes
How does one make Zucchini ribbons without a Spiralizer? Like this:Slice your Zucchini lengthways in half, then using a vegetable peeler, peel along the length of your zucchini until reaching the core. Flip and repeat on the other side.