Preheat oven to 375°F. In large bowl, combine first 5 ingredients and 1/3 cup Parmesan cheese. Form into 24 (1½-inch) meatballs. Place on a large greased baking sheet. Bake 15 minutes or until internal temperature reaches 165°F on an instant-read food thermometer.
Cook spaghetti according to package directions or until al dente. Drain. Return to pan, off heat. Add cold butter, remaining 1/3 cup Parmesan cheese and Spinach & Herb Seasoning. Stir to coat pasta until butter is melted.
Meanwhile, in small microwave-safe bowl, combine remaining 2 ingredients. Microwave, loosely covered, on HIGH 1-2 minutes or until heated through, stirring occasionally.
Twirl about 4-5 strands of spaghetti onto a fork; slide off and place skewer in center. Then skewer a meatball and dip in marinara. Place on serving plate. Repeat with remaining spaghetti, meatballs and sauce. Serve with remaining sauce for dipping.
Makes 12 servings.
Make Ahead: Prepare through step 1. Refrigerate, covered, up to 1 day. Reheat meatballs and continue with step 2 when ready to serve.