In a pan, melt half your butter and cook your mushrooms. After they've cooked through, place the mushrooms aside on a plate.
Back in the pan, melt the other half of your butter and place your garlic in. After a minute and the garlic is fragrant, add in the cut chicken. Stirring occasionally, cook chicken until lightly browned.
Pour in the quinoa and water into the pan, cover it, and bring it to a boil before turning down the heat to a simmer. The quinoa should take around 15-20 minutes to cook.
While the quinoa is cooking, in a bowl, mix together your olive oil and balsamic vinegar.
Once the quinoa is cooked, mixed your spinach in until it's a little wilted, and then add the mushrooms back into the pan.
Stir everything together and it drizzle your balsamic dressing into the pan if you are serving immediately.