In a bowl, toss the potatoes with the olive oil, garlic, salt, and pepper. Transfer to a rimmed baking sheet. Bake for 30 to 40 minutes, turning and tossing about halfway through, until the potatoes are golden brown and crunchy.
When the potatoes are about halfway done, in a separate bowl combine the corn, maple syrup, and a pinch each of salt and pepper and mix well. Transfer to a second rimmed baking sheet and place in the oven, on a separate rack from the potatoes, and bake for 15 to 20 minutes, until the corn starts to brown slightly. Remove both baking sheets from the oven and set aside.
In large saucepan, melt the butter over medium-high heat until the foaming subsides. Add the celery and onion and sauté until tender, about 5 minutes. Stir in the chipotles and flour and stir to blend well. Add the chicken broth and bring to a boil. Reduce the heat to medium-low and simmer for 8 to 10 minutes.
Reserve about a quarter of the potatoes and corn for the garnish. Stir the remaining potatoes and corn into the soup. Stir in the milk and bring it back to a simmer, stirring often, for about 5 minutes. Reduce the heat to low and stir in the Gouda, stirring until it melts completely. Taste and add salt and pepper as necessary.
Ladle the soup into shallow bowls. Garnish with the reserved potatoes, corn, and microgreens and serve.