In a large skillet, over a medium-high heat, melt butter and olive oil

Stir in onion and garlic, cook until tender

Mix in cucumber and zucchini slices, cook until softened

Stir in vegetable broth, salt, dill, and cayenne

Brint to a boil

Reduce heat to medium-low and let simmer until veggies are cooked (approximately 20 minutes)

Remove from heat and allow to sit a few minutes

Transfer to a blender, filling no more than half full

Place lid on blender and pulse a few times before blending

Puree by the batch until all has been through the blender