Activate the SEAR/SAUTE function on your pressure cooker and melt the butter in the insert. Once fully liquefied, whisk in the flour and stir constantly for about 3 minutes until it forms a smooth roux.

Incorporate the chopped onion and minced garlic, continuing to sauté for an additional 3 to 4 minutes until the vegetables have softened and are fragrant.

Pour in the warmed broth or stock, followed by the frozen vegetable mix. Season the mixture with salt, black pepper, and cayenne. Stir thoroughly to ensure all ingredients are evenly distributed.

Secure the pressure cooker lid and set to cook on HIGH pressure for 3 minutes.

Once the cooking cycle is complete, disconnect the cooker and allow the pressure to release naturally for 5 minutes. Afterward, manually release the remaining pressure with caution. If any liquid begins to escape, briefly reseal and allow a few extra minutes before trying again.

Reconnect the pressure cooker and switch back to SEAR/SAUTE mode. Add the heavy cream to the pot and stir until integrated. Simmer for 5 minutes or longer, until the mixture reaches your desired thickness.

If a thicker consistency is needed, incorporate a cornstarch slurry (equal parts cornstarch and cold water) and stir until the texture firms up. Alternatively, thin the mixture with a small amount of broth or water if it's overly thick.