01 - Preheat oven to 350°F and line a 6-cup muffin tin with paper liners.
02 - Whisk together flour, cocoa powder, baking powder, baking soda, and salt in a mixing bowl.
03 - In a separate bowl, whisk sugar, egg, milk, oil, vanilla extract, and lilac syrup until smooth and well combined.
04 - Add dry ingredients to wet mixture and stir just until combined. Avoid overmixing to maintain tender texture.
05 - Gently fold in semi-sweet chocolate chips if using, being careful not to overwork the batter.
06 - Divide batter evenly among prepared liners, filling each about 3/4 full.
07 - Bake for 16 to 18 minutes until a toothpick inserted into the center comes out clean.
08 - Let cupcakes cool in pan for 5 minutes, then transfer to wire rack to cool completely before frosting.
09 - Beat softened butter and powdered sugar until light and fluffy. Incorporate lilac syrup and mix until smooth.
10 - Frost cooled cupcakes with lilac buttercream and garnish with fresh lilac blossoms. Serve immediately or store in airtight container.