Melt the butter in a large skillet with a tight-fitting lid over medium heat.
Add mushrooms and sauté until golden and liquid has evaporated; remove from skillet and set aside.
In the same skillet, add chicken broth and liquid from the artichoke hearts; bring mixture to a boil then add chicken. Reduce skillet heat, cover and gently simmer, turning chicken while it is poaching.
When cooked through, remove chicken from skillet and keep warm. Raise skillet heat to medium-high and cook liquid until it is reduced by about half. Add artichoke hearts and sautéed mushrooms to the skillet; remove from heat and stir in yogurt.
Pour sauce over warm chicken and serve.