Prepare oven and baking dish: Preheat oven to 350°F. Lightly coat a 13- x 9-inch baking with cooking spray.
Combine dry ingredients: Stir together flour, sugar, baking powder, and salt in a small bowl until blended.
Make egg mixture: Whisk together eggs, cream, and melted butter in a medium bowl until blended.
Cook corn: Heat canola oil in a large skillet over medium-high. Add corn and onion, and cook, stirring often, until onion is softened, about 5 minutes.
Add thyme: Stir in 1 Tbsp. thyme. Remove from heat, and let cool slightly, about 5 minutes.
Make casserole mixture: Stir flour mixture and corn mixture into egg mixture.
Pour casserole mixture into baking dish: Spoon into a 13- x 9-inch (3-quart) baking dish.
Bake corn pudding: Bake in preheated oven until set and golden brown, about 40 minutes. Let stand 5 minutes before serving. Sprinkle with remaining 1 Tbsp. thyme.
