In a saucepan or microwave, heat milk, water, and margarine together to 125°F.
While the liquid heats, combine 1/3 of the flour, 3 Tbsp sugar, salt, and dry yeast in a large mixing bowl.
Add the hot liquid to the dry ingredients and beat for 2 minutes on medium speed.
Add the eggs and 1/4 cup more flour, then beat for another 2 minutes on high speed.
Stir in the remaining flour gradually to form a stiff dough (you may not need the full amount).
Turn the dough onto a lightly floured surface and knead for 8 minutes, until smooth and elastic.
Place dough in a greased bowl, turn to coat, cover, and let rise in a warm place for 40 minutes, or until doubled in size.
Punch down the dough and roll it out into a 10x12 inch rectangle on a floured surface.
Sprinkle evenly with the cinnamon-sugar mixture (1 teaspoon cinnamon mixed with 1/4 cup sugar).
Roll the dough into a 12-inch log, starting from the long edge. Use thread or dental floss to slice into 1-inch pinwheels.
Place each roll on its side on a greased or nonstick (Teflon) baking sheet, leaving about 3/4 inch between each one.
In a small bowl, rub together the topping ingredients (margarine, flour, brown sugar, cinnamon) until crumbly. Sprinkle the topping evenly over the pinwheels.
Let rise again in a warm place until doubled in volume, about 30–40 minutes.
Preheat the oven to 375°F. Bake for 20 minutes, or until golden brown.
While they bake, make the glaze by combining powdered sugar with just enough water to create a dip-friendly consistency.
Once baked, let cool slightly and dip tops of each roll in the glaze.