Place stock, ½ cup milk, grits or polenta and quinoa in a 6-qt. Instant Pot. Do not stir ingredients. Lock lid in place and set valve to SEALING position. Cook on HIGH PRESSURE for 10 minutes. Allow pressure to naturally release for 15 minutes.

Meanwhile, cut chard leaves from stems. Thinly slice stems diagonally; set aside. Stack leaves, roll into a cylinder shape and thinly slice. For chimichurri, place chard leaf strips in a food processor or blender. Add shallot, 2 Tbsp. oil, vinegar, 2 Tbsp. oregano, 2 Tbsp. parsley, garlic, salt and crushed red pepper. Cover and pulse 10 to 15 times or until shallot and garlic are finely chopped. Set aside.

Peel shrimp, leaving tails attached. Pat shrimp dry with paper towels. Heat remaining 1 Tbsp. oil in a medium skillet over medium-high heat. Add shrimp; cook for 2 minutes. Add tomatoes, reserved chard stems and 1 Tbsp. chimichurri. Cook for 2 to 3 minutes more or until shrimp reach 145°, stirring occasionally.

Place a towel over release valve on; move Instant Pot valve to VENTING position (Quick Release) to release remaining pressure. Carefully remove lid, allowing steam to escape. Whisk in butter and ¼ cup Parmesan cheese until melted; whisk in remaining ½ cup milk until creamy.

To serve, divide polenta among 4 serving bowls. Swirl in about 1 Tbsp. chimichurri into each bowl. Top with shrimp mixture. Garnish with additional oregano and parsley; serve with additional Parmesan, if desired.