Pour flour out on a large, clean surface. Make a large well in the center. Crack egg and egg yolks into the center and sprinkle with salt. Use a fork to whisk eggs together, then use the fork to start incorporating the ﬂour until a wet, sticky dough forms.
Use your hands or a bench knife to knead the dough, incorporating any ﬂour that fell to the side, until the dough feels firm and dry and can be formed into a ball, about 2-5 minutes.
Knead dough for about 10 minutes to help gluten form, adding a tiny bit of flour if too wet and a drop or two of water if too dry. Form into ball and wrap tightly with plastic. Let rough rest on countertop for about 30 minutes, or else place in fridge for up to 1 day. Let come to room temperature before continuing.
For the filling and the ravioli
For the filling: Heat oil in a large saucepan, add the garlic and spinach and cook until spinach wilts, about 3 minutes. Stir in thyme, parsley, and season with salt. Transfer spinach to a bowl with ricotta and Parmesan and mix well. Transfer ﬁlling to a pastry bag or a plastic bag with corner snipped off.
For the ravioli: Roll out dough into a thin sheet using a pasta roller (see Serious Eats article linked above for step-by-step instructions if you've never done this before). Using a cookie cutter, cut out 16 circles that are about 3½ inch in diameter.
Using your pastry bag, make a circle of the ricotta mixture about ½ an inch away from the edge of the dough, leaving the center space for the yolk. Carefully place egg yolk in center.
With your ﬁnger, wet the edges of the dough, then cover with another disc of dough and seal, pinching the edges.
Bring a large, heavily salted pot of water to boil.
In a large pan, heat butter over medium low heat until it starts to brown. Add in thyme. Reduce heat slightly to not burn butter.
Add ravioli, two to three at a time, to water and cook for about 1 minute, until ravioli floats. Using a slotted spoon, drain ravioli and transfer to butter pan immediately and brown slightly on both sides.
Sprinkle a bit of Parmesan cheese on top, if desired, and serve immediately.