Preheat oven to 400°F. Generously grease a standard 12 cup muffin tin.: The kitchen will fill with warmth as the oven comes to temperature, and a faint toasted scent will develop from the preheating metal. Preheating ensures the muffins get a quick spring in the oven, creating a domed top. One common mistake is not preheating long enough, which can lead to dense, underexpanded muffins.
In a large bowl, sift together the dry ingredients. In a separate bowl, whisk together the wet ingredients until well combined. Make a well in the center of the flour mixture and add the egg mixture, stirring only until just combined. Gently fold in the strawberries.: At this stage you will smell the sweetness of the dry mix and the bright citrus from the lemon; the batter should look slightly lumpy, not smooth. Overmixing develops gluten and makes muffins tough, so stop as soon as the dry streaks disappear. A typical pitfall is stirring too vigorously, which reduces tenderness.
Combine all the topping/filling ingredients. Use your hands to work the mixture into a coarse crumble.: When you rub the cold butter into the flour and brown sugar , you will feel it break into pea sized crumbs, and the aroma will become richer and toasty. Getting a coarse texture is important because it bakes into a crunchy, slightly caramelized streusel. Avoid warming the butter with your hands too much, or the streusel will clump and not create the desired texture.
Spoon the muffin batter, about 1/4 cup, into each muffin tin. Top with streusel, pressing it gently down into the top of the muffin batter in each cup. Bake at 400 degrees for 12 to 15 minutes, or until muffins spring back when pressed lightly. Remove from oven. Cool slightly, then transfer carefully to a wire rack.: You should hear a faint crackle as the streusel toasts, and the tops will turn a golden brown. The interiors will smell of warm cinnamon and strawberries . Testing for spring back is more reliable than timing alone, because ovens vary. A frequent error is overbaking, which dries the crumb, so start checking at the earlier end of the time range.
Whisk together all of the frosting ingredients. Drizzle over the top of the muffins and enjoy every single delicious bite.: When you whisk the cream cheese with powdered sugar and a touch of milk , the frosting becomes glossy and smooth, releasing a sweet, tangy aroma. The drizzle should form ribbons across the tops, and a little cool frosting will set into a delicate shell. If the frosting is too thin, add a bit more powdered sugar ; if it is too thick, add a few drops of milk . A common slip is overheating the frosting or adding too much liquid, which makes it run off the muffins.