Preheat Oven: Start by preheating your oven to 375°F (190°C). This ensures that your oven is at the right temperature for baking the muffins evenly.

Prepare Muffin Tin: Line a muffin tin with paper liners or grease each cup well. This step is essential for easy removal of the muffins and to prevent sticking.

Mix Dry Ingredients: In a large bowl, combine all-purpose flour, granulated sugar, baking powder, and salt. Whisk them together to ensure even distribution of the leavening agents and to prevent clumping.

Blend Wet Ingredients: In a separate bowl, whisk together the lightly beaten egg, milk, melted unsalted butter, and vanilla extract. Mixing these ingredients separately ensures that the egg is well distributed and the butter is evenly incorporated.

Mix Wet and Dry Ingredients: Gently fold the wet ingredients into the dry ingredients. Mix just until combined; be careful not to overmix. Overmixing can lead to dense muffins, so stop mixing as soon as there are no visible streaks of flour.

Add Cherries: Stir in the chopped fresh or frozen cherries. If using frozen cherries, do not thaw them to prevent the batter from becoming too moist. The cherries should be evenly distributed throughout the batter.

Mix Streusel Ingredients: In a small bowl, combine packed brown sugar, all-purpose flour, and ground cinnamon.

Cut in Butter: Add softened butter to the mixture. Use a pastry cutter or your fingers to cut the butter into the dry ingredients until the mixture resembles coarse crumbs. This step creates the crumbly texture that is characteristic of a streusel topping.

Fill Muffin Cups: Spoon the batter into the prepared muffin cups, filling each about two-thirds full. This allows room for the muffins to rise without overflowing.

Add Streusel Topping: Generously sprinkle the streusel topping over the batter in each muffin cup. The topping will bake up into a sweet, crunchy layer that contrasts beautifully with the soft muffin.

Bake: Place the muffin tin in the preheated oven and bake for 20-25 minutes. The muffins are done when a toothpick inserted into the center comes out clean and the tops are golden brown. Baking times may vary slightly depending on your oven, so keep an eye on them towards the end of the baking time.

Cool: Allow the muffins to cool in the pan for about 5 minutes before transferring them to a wire rack. This brief cooling period helps the muffins set and makes them easier to remove from the pan without falling apart.