Make sure you don't eat muffins while hot as the caramel inside the eggs will be very hot. When Easter eggs are not available, use Rolo chocolates or pieces of caramel-filled chocolate. This is from Super Food Ideas.
Preheat oven to 180°C; line a 12 x 1/3-cup capacity muffin pan with paper cases.
Sift flour into a large bowl. Stir in sugar. Whisk butter, milk, eggs and vanilla essence together.
Add butter mixture to dry ingredients. Use a wooden spoon to mix until just combined (don't over-mix or your muffins will be tough). Spoon batter into cases so each is one-third full. Place an unwrapped Easter egg into the middle of each muffin. Spoon over remaining muffin batter.
Bake muffins for 18 to 20 minutes, or until light golden and cooked through. Stand in pan for 10 minutes before turning onto a wire rack to cool completely.