01 -
Melt 30 ml of butter with 30 ml of olive oil in a large nonstick high-sided skillet over medium-low heat. Add sliced onions and allow to cook undisturbed for 15 minutes. Stir and continue to cook for an additional 15 minutes, then continue caramelising for another 10-15 minutes until deep golden and sweet.
02 -
Increase the heat to medium, add minced garlic and cook for 1 minute. Add salt, pepper, tarragon, and thyme; cook for 1 minute longer. Remove pan from heat and carefully add brandy or white wine. Return to heat and cook until liquid is evaporated, about 5 minutes. Stir in Worcestershire sauce and remove from heat. Set onions aside.
03 -
In a medium pot or large saucepan over medium-high heat, add mushrooms dry and sauté until browned, about 5-10 minutes. Add remaining 15 ml butter and 15 ml olive oil. Once melted, add uncooked rice and cook for 5 minutes, stirring to lightly brown.
04 -
Add baby spinach and cook for 1 minute until just wilted. Pour in chicken stock and bring mixture to a simmer. Reduce heat to low, cover with a lid, and cook for 15 minutes.
05 -
Remove lid from rice, stir in heavy cream and torn cooked chicken. Heat through until just hot.
06 -
Lightly spray a 23x33x7 cm casserole dish with nonstick cooking spray. Transfer rice mixture to dish and spread evenly. Top with the caramelised onions, then sprinkle shredded Gruyère cheese over the top. Place under broiler until cheese is melted, bubbly, and golden brown.
07 -
Serve immediately while hot and bubbly.