Heat olive oil in a large skillet over medium-high heat.
Season the chicken breasts with salt and pepper, then add them to the skillet.
Remove the chicken from the skillet and set aside on a plate.
Add chopped onions to the skillet and sauté until soft and translucent, about 3-4 minutes.
Add minced garlic and thyme, cooking for an additional minute until fragrant.
Pour in the Riesling wine, scraping the bottom of the skillet to deglaze it.
Let the wine simmer for 3-4 minutes until slightly reduced.
Stir in the heavy cream, mixing well until combined.
Return the chicken to the skillet, coating it well with the sauce.
Simmer for an additional 5 minutes to let the sauce thicken further.
Serve garnished with chopped parsley for freshness.