To prepare the pasta dough:
Take the listed dough ingredients and place them together in a food processor. Process it till the mixture leaves the sides of the bowl. (You can also opt to knead this mixture.)
Then place this dough on a floured surface and knead for a few minutes using your hands till the dough is smooth to touch. (Add a few drops of water if the dough becomes too dry.)
Now, divide this dough into 4 parts equally and shape them into discs. Then wrap them in a plastic wrap and rest for 1 hour or so.
To make the ravioli filling:
Put the listed ravioli ingredients into a blender and blend it well. Then add in the egg yolks and blend again.
Roll the dough discs into thin sheets with the help of a pasta machine. Place a tablespoon of the filling with 1 and 1/2 inches of space apart on one of the sheets.
Brush some egg whites on top of the dollop and place another sheet directly on top. Gently press the area around the filling to remove any air pockets and seal the sheets.
With the help of a ravioli cutter or knife, carefully cut out ravioli squares. Sprinkle some flour on top so that the dough doesn't stick.
Boil water in a cooking bowl with some salt, once the water starts boiling put in the ravioli pastas and wait for them to float to the top. This could take about 3 to 4 minutes. Drain well and keep aside.
To make the tomato sauce, heat the olive oil and butter in a pan. Once the oil is hot, add in the onions and garlic together. Sauté and cook for about a minute or so.
Next pour in the tomato puree, salt, pepper, and sugar. Combine these ingredients well together. Lower the flame and let it simmer and cook for 30 minutes or so while stirring occasionally. Remove it from the heat and stir in the cream.
Place the pasta on a serving plate and top it with the tomato sauce. Garnish with some parsley or basil leaves and serve it hot.