Preheat the oven to 375 degrees F. Lightly butter 6 (3/4 cup/6-ounce) ramekins with 4 teaspoons of the butter. Combine the breadcrumbs and Parmesan cheese and use to dust the bottoms and sides of each ramekin. Set inside a roasting pan large enough to hold the cups without touching. Lightly grease a baking sheet with 1 teaspoon of the butter and set aside.

In a medium saucepan, melt the remaining 3 tablespoons of butter over medium heat. Add the shallots and cook until soft and fragrant, about 1 minute. Add the flour and cook, stirring constantly with a wooden spoon, until it thickens slightly and forms a light roux, 2 to 3 minutes. Add the milk, and bring to a boil. Simmer, whisking, until thick, 2 to 3 minutes. Remove from the heat. Add the egg yolks 1 at a time, whisking after each addition. Add the cheese, tarragon, salt, and pepper, and stir to incorporate.

In a large bowl, beat the egg whites and cream of tartar until stiff peaks just form. Stir 1/4 of the egg whites into the egg yolk mixture. Gently fold the remaining egg whites into the yolks in 3 additions. Divide among the prepared custard cups and fill the roasting pan with warm water to come half way up the sides of the ramekins. Bake without opening the oven door until slightly puffed and golden brown, about 20 minutes. Remove from the oven and transfer to a wire rack. Let rest uncovered for 30 minutes. Run a thin, sharp knife around the edges of the ramekins to release the souffles. (Note: souffles can be covered at this point in plastic wrap and refrigerated overnight.)

Increase the oven temperature to 425 degrees F. Bake the souffles until puffed and heated through, 5 to 7 minutes. Remove from the oven.

Add the dried cherries and pine nuts to the spinach and stir to combine. Divide the wilted spinach mixture among 6 salad plates. Arrange 1 souffle on each plate and serve.

Heat butter in a wide 6-quart heavy pot over moderate heat until foam subsides, add garlic and balsamic vinegar and cook for 30 seconds. Then cook spinach, stirring, until just wilted but still and bright green, 2 to 3 minutes. Remove from the heat and season with salt and pepper. Cover to keep warm until ready to serve.