Add fennel seeds to skillet; toast over medium, stirring often, until fragrant, about 2 minutes. Remove skillet from heat; let cool slightly, about 2 minutes. Stir in shallots & green onions, vinegar,herbs, garlic, sugar, crushed red pepper, remaining 1 T oil, and remaining 2 teaspoons salt until well combined. Return to heat over low; cook, stirring occasionally, until mixture is just warm, 3 to 5 minutes. Serve over brie