Preheat oven to 375 degrees F. Grease a 9-inch deep-dish pie plate; set aside.
Place cauliflower in a food processor in batches. Cover and pulse each batch until crumbly and mixture resembles the texture of rice.
In a very large skillet, heat 1 tablespoon of the oil over medium-high heat. Add the cauliflower and cook, stirring occasionally, about 4 minutes, or until cauliflower is tender and starting to brown.
In a medium bowl, combine the cauliflower, 1 egg, 1/2 cup of the cheese, the panko, and 2 tablespoons chives. Press mixture onto the bottom and up the sides of the prepared pie plate.
In the same skillet, heat remaining 1 tablespoon of oil over medium heat. Add sweet pepper and cook for 2 minutes, or until it begins to soften. Add sausage and onion and cook for 5 minutes, stirring occasionally, until onion softens and sausage begins to brown.
Spoon sausage mixture and remaining 1/2 cup cheese into cauliflower crust.
In a medium bowl, whisk together remaining 4 eggs, whipping cream, and flour. Pour over sausage mixture in crust.
Bake, uncovered, for 30 to 40 minutes or until a knife inserted near center comes out clean. Let stand on a wire rack for 10 minutes before serving. Sprinkle with additional chives, if desired.