Egg wash is a mixture of egg and water brushed on to breads or pastries to enhance their color and give them a shine. Yolks or whites only can be used in stead of whole eggs. Milk can be substituted for water. I've never tried cream or half and half, but I bet that would be tasty on any sweet baked goods.
The basic recipe is one egg to two teaspoons of milk or water. However, don't fret the accuracy. Scramble an egg in a cup. Add a splash of your desired liquid. Swoosh around. Brush to your heart's content.