Preheat oven to 350 degrees. Spread 1/2 cup corn kernels on rimmed baking sheet; roast until golden, 10 to 12 minutes.
In stockpot over medium-high heat, cook bacon until crisp and fat is rendered, 4 to 6 minutes. Transfer to paper towels. Pour off all but 4 tablespoons fat from pot.
Add onions, celery, jalapenos, thyme, and bay leaf to stockpot. Cook over medium heat until vegetables are soft, 10 to 12 minutes. Add chicken stock; bring to a boil. Reduce to simmer; cook 20 minutes.
Add remaining corn; simmer until tender, about 7 minutes. Remove from heat; discard thyme and bay leaf. Season with salt and pepper. Transfer to blender; process until smooth. Strain; transfer to clean pot. Add half-and-half; simmer until hot. Adjust seasoning. Garnish with chives, reserved bacon, and roasted kernels.