Preheat oven to 350° F. Prepare a muffin tin by either spraying with nonstick cooking spray or lining with muffin papers.
Add butter to a mixing bowl and cream with an electric mixer for 2 minutes. Add brown sugar and continue to mix until well incorporated, stopping to scrape down the sides as necessary.
Add the egg to the butter and mix in thoroughly.
Pour in the buttermilk and mix, then the honey. Batter will be very runny.
Stop the mixer and add in the flour, cocoa, and baking soda. Mix on low speed until just combined. Stop mixer and add in the flax seed. Mix on low speed for 1 minute, scraping down the sides as needed to ensure it is all combined.
Stop mixer and add in strawberries. Mix on low speed for 1 minute or fold in by hand using a spatula.
Using an ice cream scoop, fill each muffin hole with batter to be ⅔ full. Once all batter has been used, gently tap muffin pan on counter to level batter.
Bake for 16-17 minutes or until cake tester comes out clean from center of muffins. Recommend rotating muffin pans front to back and side to side half way through baking.
Remove from oven and let cool in pan for 5 minutes. Then remove and let cool completely on wire cooling rack.