To make the crumb topping, whisk together the flour, sugar, and salt in a medium bowl. Add the butter. Using your fingertips, work the butter into the dry ingredients until large, moist crumbs begin to form. Refrigerate the topping until you're ready to use it.
Preheat the oven to 350°. Coat a 9-inch springform pan with nonstick spray.
To make the cake, in a medium bowl, whisk the flour, cornmeal, baking powder, baking soda, and salt; set aside.
Using a standing or electric mixer, beat 3/4 cup of sugar and butter in a medium bowl until light and fluffy, 3–4 minutes. Beat in the vanilla. Add the eggs one at a time, beating to blend between additions and occasionally scraping down sides of bowl, until pale and fluffy, 3–4 minutes more.
With the mixer on low speed, add the dry ingredients to the bowl in 3 additions, alternating with buttermilk in 2 additions, beginning and ending with the dry ingredients.
Pour half of the batter into the prepared pan and smooth out the top. Whisk remaining 3 Tbsp. sugar and cinnamon in a small bowl; sprinkle evenly over batter in pan. Spoon the remaining batter over the top and smooth it out again.
Pour the strawberries evenly over the batter. Break apart the crumb topping over the strawberries.
Bake the cake until the top is golden brown and a tester inserted into the center comes out clean, 55–60 minutes.
Let the coffee cake cool completely in the pan.
Store the cake in an airtight container at room temperature for up to 3 days.