Prep the oven and pan: Heat oven to 350°F (175°C). Line a 12-cup muffin tin with paper liners.
Mix dry ingredients: In a large bowl, whisk flour, sugar, baking powder, baking soda, and salt until combined.
Mix wet ingredients: In another bowl, whisk melted butter, eggs, buttermilk, and vanilla until smooth.
Combine batter: Pour wet into dry and stir just until no dry streaks remain.
If using fresh strawberries, fold them in gently. Do not overmix.
Fill and bake: Divide batter among liners (about 2/3 full). Bake 16–20 minutes, until tops spring back and a toothpick comes out clean. Cool in the pan 5 minutes, then move to a rack to cool completely.
Make the crunch topping: In a bowl, combine crushed cookies, freeze-dried strawberries, melted butter, and a pinch of salt.
Toss until the mixture clumps slightly. Set aside.
Make the frosting: Beat butter until creamy and pale, 2–3 minutes. Add powdered sugar, crushed freeze-dried strawberries, vanilla, and a pinch of salt.
Beat on low, then increase speed. Add cream 1 tablespoon at a time to reach a smooth, pipeable consistency.
Optional filling step: Use a small knife or cupcake corer to remove a 1-inch plug from the center of each cupcake. Spoon in 1–2 teaspoons strawberry jam.
Replace the top piece.
Frost: Pipe or spread a generous swirl of strawberry frosting on each cooled cupcake.
Add the crunch: Gently press the crumble onto the sides and a bit on top of the frosting so it sticks. Work over a tray to catch excess.