For one recipe quantity (so ⅓ cup/84g puree), use around 7oz/200g of beet, either one or two beet depending on size. Place the beet/beetroot in a piece of foil in a baking dish and drizzle over a small amount of oil (or you can leave as it is if you prefer). Wrap with the foil then roast in the oven until a knife inserted into the middle goes in easily as it is tender. This can take around an hour, or more if the beet is large, maybe a little less if you use two smaller beet. Set aside to cool.
Once the beet is cool, peel off the skin and cut the beet into chunks. Place the beet in a blender or use an immersion blender to blend into a smooth puree. Measure out ⅓ cup (80ml) of the puree to use for the pasta - if there is more, use for something else.
To make the beet pasta
Place the flour, eggs, egg yolk, beet puree and salt in a food processor and pulse until well mixed, scraping down as needed. Alternatively, you can mix by hand by placing the flour on a clean surface, creating a well, then adding the other ingredients in the middle.
Pulse the mixture, if using a food processor, until the dough comes together. If mixing by hand, use a fork to break up the egg and gradually mix in the flour.
Remove the dough to a floured surface and knead with floured hands for about 5 minutes. It should be soft but not sticky - if it is, add a little more all-purpose/plain flour as you knead.
Wrap in plastic/cling film and allow to rest at room temperature for around 30 minutes. At this stage, you can keep the dough in the fridge for a day or two until ready to use. Then, let it rest at room temperature around 30 minutes before rolling.
When ready, cut a chunk from the dough (around ⅙ to ¼ at a time) and cover the piece you aren't working with with cling film/wrap or a damp cloth to save it drying out.
As you work with each piece, flatten it out slightly, dust with flour then put it through your pasta roller on the widest settings a few times (around 2 - 3 times) until smooth, dusting with flour in between if at all sticky. This is a relatively soft dough so you will likely need a bit extra flour. Then move up the settings rolling ideally twice at each setting (once from either end) until you get to the thickness you would like. On my machine, I typically roll to about '5' or '6'.
Then, either use the cutter attachment or hand cut if you want to make into linguine/fettuccine and place the ribbons onto a floured tray or surface in little stacks or laid flat. Alternatively, cut into other pasta shapes eg bow ties.
Once all is done and ready to cook, place handfuls at a time in boiling water, helping the pieces to separate as you add them, for around 2-3 minutes until they come to the surface and are cooked.
Serve with your preferred sauce (we like it with browned butter or walnut sauce, it's also good with a cream sauce).