Preheat oven to 350 degrees.

Place tomato slices in an even layer on an parchment-lined baking sheet and drizzle lightly with olive oil. Roast for about 1 hour and 15 minutes, or until pieces are shrunken, dried, and starting to char at the edges. Remove from oven and place in the bowl of a food processor fitted with a steel blade.

While tomatoes are roasting, place shallot slices and whole garlic cloves in a foil packet and toss with a light drizzle of olive oil and a pinch of salt. Wrap tightly and roast for about 30 minutes, until fragrant, softened, and slightly browned. Remove from oven and place in the food processor with the tomatoes.

Add the chives and the crema or sour cream to the food processor and process everything to a smooth consistency. Season with salt to taste and serve, or store in the refrigerator, preferably in a glass container.

Whisk together the flour, baking powder, and salt in a large bowl.

In a separate bowl, whisk together the milk, sour cream, and egg. Whisk the wet ingredients into the dry ingredients, mixing just until you have a smooth, uniform batter. Fold in the corn and green onions.

Heat a heavy-bottomed skillet or griddle over medium heat. Melt about 1/2 tablespoon of butter on the pan/griddle (do this prior to frying each batch of corn cakes). Using a 1/4-cup measure for regular-sized cakes, or a tablespoon-sized measure for bite-sized cakes, portion cakes out onto the cooking surface. Fry corn cakes for approximately 3 minutes on the first side, until air holes appear across the top of each corn cake and their shapes are set and matte colored. Flip and cook 3-4 minutes more, until cakes are cooked through. Serve with roasted crema.