Put the saffron in a small ramekin or cup and pour ¼ cup of boiling water over it. Let it steep while you cook the pasta and start the sauce.
Cook your pasta in a large pot of well salted water. Reserve a mug of the pasta water before draining.
Heat the olive oil in a large skillet that will fit all the pasta in at the end, over a medium heat.
Gently fry the garlic for a minute or two being careful not to brown.
Lower the heat slightly, add the wine and simmer until reduced by half, 1 - 2 minutes.
Add the butter in three seperate lots, whisking well in between so it becomes a nicely emulsified sauce. I like to shake the pan with my left hand and whisk with my right.
Add the saffron and steeping liquid and simmer for 2 minutes.
Add the cream and bring to a very gentle simmer (adjust your heat if you need).
Add the grated parmesan in a couple of lots, letting it melt into the cream before adding more.
Add the lemon juice and stir quickly.
Let it gently bubble for a couple of minutes to thicken slightly.
Add the cooked pasta straight in, giving it a good toss in the sauce.
Let the pasta gently bubble away in the sauce for a minute or two to thicken. It will continue to thicken off the heat so go for saucier than you think. Add a splash of pasta water if you need to loosen.
Divide between plates, top with extra parmesan and some lemon zest if you wish.