Coat a 6-compartment, 2-inch silicone ice cube tray liberally with cooking spray; set aside. Cook bacon in a medium skillet over medium-high, stirring occasionally, until almost crispy, about 5 minutes. Add broccoli; cook, stirring occasionally, until almost tender, about 1 minute. Transfer bacon and broccoli to a medium-size heatproof bowl. Stir in cheese and half-and-half. Add eggs, salt, and pepper; stir to combine. Pour mixture evenly into prepared ice cube tray.

Pour water into a programmable pressure multicooker (such as Instant Pot). (Times, instructions, and settings may vary according to cooker brand or model.) Place ice cube tray on cooker trivet, and place inside cooker. Cover cooker with lid, and lock in place. Turn steam release handle to SEALING position. Select STEAM setting. Select HIGH pressure for 16 minutes. (It will take 5 to 10 minutes for cooker to come to pressure before cooking begins.)

Let the pressure release naturally for 13 minutes. Carefully turn steam release handle to VENTING position, and let steam fully escape (float valve will drop). (This will take 30 seconds to 1 minute.) Remove lid from cooker. Remove ice cube tray from cooker. Remove cooked egg cubes from tray; garnish with chives.