Heat oven to 350°F (325°F for dark or nonstick pans). Generously grease and lightly flour 12 mini fluted tube cake pans or 12 jumbo muffin cups (do not spray with cooking spray).
In large bowl, beat cake mix, water, oil and eggs with electric mixer on low speed 30 seconds, then on medium speed 2 minutes, scraping bowl occasionally. Fold in pecans and 1/2 cup toffee bits. Divide batter evenly among mini pans.
Bake 18 to 23 minutes or until toothpick inserted in center of cake comes out clean. Cool 10 minutes; remove from pans to cooling rack. Cool completely, about 1 hour.
In 1-quart saucepan, melt butter over medium-high heat. Stir in brown sugar, corn syrup and milk. Heat to rolling boil over medium-high heat, stirring frequently; remove from heat. Immediately beat in powdered sugar and vanilla with whisk until smooth. Immediately drizzle about 1 tablespoon glaze over each cake; sprinkle each with 1 teaspoon toffee bits. Store loosely covered.