1- Place a large skillet over medium heat. Place the olive oil and butter and allow them to melt together. Roughly chop the mashed garlic and add it to the pan. Add zucchini cubes.
2- Cook for 15 to 20 minutes, or until the zucchini starts to soften. Strip thyme leaves off there stems and add them to the pan.
3- Reduce the heat and continue to cook stirring often . The goal is to cook the liquid out of the zucchini and melt it into a flavorful , spreadable paste. If at any time, the zucchini starts to town and stick, add a splash of liquid ( water is fine, though if you have an open bottle, a little white wine is also delicious) and reduce heat a it more.
4- Total cooking time should be right about an hour.
5- Once cooked, divide the spread between 1/2 pint jars. It will keep up to 2 weeks in the fridge or a year in the freezer.