Start by making the Streusel. In a medium bowl, stir together the sugar and flour. Then using a pastry blender, cut in the cold butter until you get the consistency of course sand. Refrigerate until ready to use.
Preheat the oven to 350 degrees F. Spray a muffin tin with cooking spray and line 12 cups with liners. Set aside.
Next make the muffins. In a microwave safe bowl, warm the heavy cream for a minute, then steep the tea bags in and set aside until ready to use. Next in a medium bowl, mix the flour, baking powder and salt. Set aside.
In the bowl of a stand mixer, cream the butter and sugar until light and fluffy. This should take about 2 minutes. With the mixer on low speed add in the eggs one at a time, then the vanilla. Remove the tea bags from the heavy cream and carefully stream in the heavy cream into the mixer bowl. Mix until incorporated. Next, with the mixer still on low speed, mix in the flour/baking powder/salt mixture and mix just until incorporated.
With the mixer off, fold in the blueberries. Depending on the size of the blueberries you have will determine how many muffins this will make.
Using an ice cream scoop or a 1/4 measuring cup, fill the muffin tins 3/4 of the way full. Sprinkle streusel on top of each muffin.
Bake until a toothpick inserted into the center of a muffin comes out clean. About 22-24 minutes. Serve warm with a smear of butter.