Beat butter, salt and vanilla until fluffy. Add milk, beat in sugar. Blend until stiff. Dust with brown sugar. Knead until smooth.
Take about 1/3 of the mixture, and add yellow food coloring. Shape the yellow colored portion into approx. 20 balls. This will be the "yolk" of your egg. Next divide the white portion into about 20 pieces of dough. Form the white around the "yolk" to form an oval white egg. Dry at room temperature on paper towels for 24 hours.
Melt chocolate in double boiler or in microwave until smooth. Dip eggs in chocolate. Note: about 1-lb. paraffin wax may be added and melted with chocolate to prevent chocolate from melting in your hands. (Paraffin is optional.) Once dipped, cool at room temperature. Refrigerate after cool.
When sliced or bit into, your Cream-Filled Chocolate Easter Eggs will have a white cream filling with a yellow filling that appears to be the yolk. It's really cool.