Dice the onions and mince the garlic, then set aside. Trim the asparagus and cut into 2-inch pieces. Cut the chicken thighs into bite-sized pieces (about 1.5 to 2 inches) so they cook evenly and blend better with the rice—this also helps the chicken cook faster and more consistently than leaving them whole. Have all spices measured and ready before you start cooking.

Turn the Instant Pot to sauté mode and melt the butter. Add the diced onions and cook for 4-5 minutes until they become translucent and soft, stirring occasionally. Stir in the minced garlic and cook for just 20 seconds until fragrant—this short cooking time prevents the garlic from burning and keeps its flavor bright. Add the brown rice and stir constantly for 1-2 minutes to coat it in butter and lightly toast it; this adds a subtle nutty flavor that enhances the final dish.

Pour in the chicken stock and add the dried basil, garlic powder, salt, black pepper, and red pepper flakes. Stir well to distribute the seasonings evenly through the rice and liquid. Nestle the cut chicken pieces on top of the rice mixture in an even layer—don't stir them in. The chicken will cook gently on top while the rice steams below, keeping everything moist and preventing the chicken from drying out.

Seal the Instant Pot lid and set the valve to sealing. Cook on high pressure for 22 minutes. Once the timer goes off, let the pressure release naturally for 10 minutes (this allows the rice to finish absorbing moisture and the chicken to stay tender), then carefully vent any remaining pressure by switching the valve to venting.

Carefully open the pot and give everything a gentle stir. Add the cut asparagus pieces and freshly grated Parmesan cheese, stirring to distribute them evenly throughout the rice and chicken. I like to add the lemon juice at this point because the acidity brightens the flavors and cuts through the richness of the cheese and butter. Cover the pot (you don't need to seal it) and let it sit for 2-3 minutes so the asparagus steams and becomes tender while the cheese melts into the rice.

Remove the lid and stir once more to combine everything. The asparagus should be tender but still have a slight bite to it. Ladle into bowls and serve immediately while hot.