Using a dutch oven or heavy bottom pot with tight fitting lid, over medium/high heat, add 2 Tbsp olive oil and 2 Tbsp butter. Add onions and sauté until translucent (5 min) then add sliced mushrooms and cook until liquid has evaporated and mushrooms are lightly golden (8-10 min). Add in 2 pressed garlic cloves and stir (1 min).
Add 1/2 cup white wine and cook until mostly evaporated (2-3 min). Stir in the rice then add 4 cups broth, 2 Tbsp butter, 1 tsp salt and a pinch of black pepper.
Bring to a boil then reduce heat to low, cover and simmer until rice is fully cooked through and liquid absorbed (15-18 min). Give the rice a quick stir and serve garnished with dill or parsley.