Preheat oven to 350°.
Wrap the outside of a 9 inch springform pan with foil, then spray the inside with cooking spray. In a medium saucepan, add potato and 1 teaspoon salt; cover with water. Cook over medium-high heat until tender, about 5 minutes. Drain well.
In a large skillet, heat oil over medium-high heat. Reduce heat to medium-low, and add onion and garlic allow to saute, stirring occasionally for about 2 minutes
Add potatoes and green onion to cooked onion mixture, and stir gently to combine. Season with sea salt and black pepper to taste. Continue to cook the combination for 4-5 minutes.
Place 2/3 of the mixture in the bottom of your spring form pan to make a nice layer, reserve the remainder.
Add a little more olive oil to the hot pan and add in the shrimp and creole seasoning. Cook shrimp until almost done. It's important not to overcook the shrimp!
Add the shrimp to the springform pan on top of the potato layer, then add the remainder of the potatoes and shredded jack cheese.
In a large bowl, whisk together eggs, cream, ½ teaspoon salt. Add softened butter in small pieces and whisk well.
Pour egg mixture over ingredients.
Bake until top is golden brown and mixture is set, about 45 minutes.
Let stand in pan for 10 minutes and gently remove from springform pan. Run a knife along the edges of pan to help release the tortilla.
Garnish with white parts of scallions and cilantro.
Serve warm or at room temperature.