In a stand mixer bowl, dissolve 1 teaspoon of granulated sugar in warm water. Lightly sprinkle in yeast. Let stand for 10 minutes or until foamy. Whisk in the remaining sugar, milk, 1/4 melted butter (50ml), eggs, vanilla, and salt. Add 3 cups flour. Using dough hook attachment, mix until it forms a soft sticky dough.
Knead dough, on medium low speed, adding in remaining flour as needed, for 10 minutes or until the dough is smooth and elastic. Knead in the chocolate chips. Transfer to a greased bowl, cover and let rise in a warm, draft free area, about 1 hour or until doubled in volume.
Grease a 10-inch bundt pan. Place remaining melted butter in a small bowl. In a separate bowl, toss the brown sugar and toffee bits together. Transfer the dough to a lightly floured surface and knead 4 to 5 times to release any excess air.
Pinch off small pieces of dough, about 1-inch, and roll into balls (about 36 balls). Coat each ball in the butter, then lightly coat in the brown sugar mixture. Layer the balls evenly into bundt pan. If you have any of the brown sugar mixture left, sprinkle evenly over the coated balls. Cover with plastic wrap, and let rise in refrigerator overnight.
Preheat oven to 350 degrees F. Bake for about 30 to 35 minutes, or until top is golden. Cool in pan for 5 minutes, then turn out onto serving plate. Serve warm.
