Finely chop the onion, peel and dice the carrots, dice the celery, mince the garlic, and peel and cube the potatoes. Shuck and remove kernels from the corn if using fresh corn.

Place the corn, onion, carrots, celery, garlic, and cubed potatoes in the slow cooker. Pour in the broth, add thyme and bay leaf, and season with salt and pepper to taste. Stir to combine all ingredients.

Cover and cook on low for 7-8 hours or high for 3-4 hours, until the potatoes are tender and flavors are melded together.

Remove the bay leaf. Use an immersion blender to partially blend the chowder, leaving some chunks for texture. Stir in butter and cream or half-and-half, and adjust seasoning if needed.

Serve the chowder warm, topped with optional garnishes like crispy bacon or smoked ham, shredded cheddar cheese, and chopped chives for added flavor and presentation.