Preheat oven to 425°F. Toss cauliflower with half the oil and half the salt. Arrange on a small baking sheet.
Roast, turning occasionally, for 20 to 25 minutes or until tender and golden brown. Cool and roughly chop; set aside.
Meanwhile, heat remaining oil in a skillet set over medium-high heat. Sauté spinach for 1 to 2 minutes or until wilted. Cool completely, squeeze dry and chop.
Reduce oven temperature to 400°F. Beat cream cheese with lemon juice, oregano and garlic until light and fluffy with electric beaters. Beat in sour cream, mayonnaise and Parmesan cheese until smooth. Stir in cauliflower, spinach, chives and parsley until blended.