Coarsely grate the zucchini. Let it drain in a colander for 3 to 4 minutes or until you are ready to begin cooking. To hasten cooking time, squeeze the water out of the zucchini by wringing it in a clean cloth towel.
In a deep skillet, heat the olive oil/butter. Sauté the shallots briefly. Add the zucchini and toss. Cook and stir over medium to medium-high heat until the zucchini reaches a spreadable consistency. If you scorch the bottom, turn the flame down! (And scrape those delicious bits into the marmalade for added flavor.) The zucchini will hold its bright green color and slowly caramelize into a nice vegetable jam.
Enjoy on toast, or as a side dish all summer long!