Preheat oven to 400 degrees Fahrenheit. Line a sheet pan with foil or Gefen Parchment.

Wash and trim ends off zucchinis. Using a hasselback cutter or guide, slice halfway through. Cut zucchinis into two-inch lengths. Sprinkle salt on the zucchinis; be sure to get it in between the cuts.

Bake for 20 minutes to soften. Remove from oven and cool for five minutes.

In a large skillet, heat oil and add onions. Sauté onions until golden, then add garlic. Add diced kielbasa and sauté until it starts to crisp around the edges. Remove from heat. Add parsley and mayonnaise. Stir to combine.

Using approximately one tablespoon filling for each zucchini piece, stuff filling between the slices. Sprinkle generously with panko and bake for an additional 20 minutes until golden. Serve hot.