Place bacon in a large skillet and cook over medium-high heat, turning occasionally, until evenly browned, about 10 minutes. Drain bacon slices on paper towels; crumble.
Combine bacon, broccoli, and raisins together in a plastic bowl with a tight-fitting lid.
Combine cream, sugar, and flour together in a skillet over medium heat; cook, whisking constantly, until sugar and flour are dissolved, 2 to 3 minutes. Slowly whisk vinegar into cream mixture until incorporated.
Whisk about 1 tablespoon cream mixture and egg together in a bowl; add about 2 more tablespoons cream mixture until egg starts to warm. Whisk egg mixture into cream mixture in skillet; cook until dressing is thickened, about 5 more minutes.
Fill a large bowl with ice and add water, creating an ice bath. Place skillet in ice bath to cool dressing.
Pour dressing over broccoli mixture. Secure lid on bowl and shake until salad is evenly coated. Refrigerate until chilled, at least 30 minutes.