Grease a 9x9 square baking pan or 9-inch cake round with butter and line it with parchment paper.
In a medium bowl whisk together the flour, baking powder, baking soda, and salt.
In a large bowl or stand mixer, cream the butter and sugar until light and fluffy. Add the eggs in one at a time, then scrape down the bowl, and add the buttermilk in 2 additions, alternating with the flour mixture. Mix until well combined.
Gently fold in the strawberries using a rubber spatular. Transfer the batter to the prepared pan. Rest the batter for up to 30 minutes.
Preheat the oven to 350℉, then place the rested batter in the oven and bake for about 45-50 minutes, until the top of the cake is firm and a tester comes out clean.
Cool the cake in the pan placed on a wire rack for 30 minutes, then carefully turn it out onto the rack, remove the parchment, and cool completely.
Then, make the icing: Beat together the cream cheese and butter until smooth. Sift in the powdered sugar, and add a little milk if you think it is too thick. When the cake is completely cooled, place it on a serving plate and spread the icing evenly over the top.
Notes
Tips
Fold in the strawberries gently. Once you've cut up the strawberries, you'll want to take a gentle hand when adding them to the batter. This will prevent the juices from coloring the cake and help the strawberries stay intact, making for more intense bites of flavor.
Wash and dry the berries. You should always wash produce before including it in a recipe, and even though strawberries are a bit delicate, they'll also need a rinse. Place the strawberries in a colander under cold running water, then drain them and place them on a clean dish towel or paper towel to dry before you dice them.
Try other berries. This is a lovely buttermilk cake that can be used as a foil for all kinds of fruit. Try making it with peaches, raspberries, blackberries, and more.
Rest the batter. Let the gluten free batter rest for up to 30 minutes to allow the oat flour to fully hydrate. If you're short on time, resting the batter while the oven preheats will go a long way toward creating that beautiful gluten free crumb.
What kind of pan? I like baking this cake in a 9x9-inch square pan so I can cut out tidy squares of cake. But, you can also bake it in a 9-inch cake round. I like to line the bottom of whatever pan I use with parchment paper so that the cake releases easily when I remove it from the pan.
Oat flour substitute - You can use your preferred 1:1 gluten free baking flour - I like my homemade gluten free flour blend - in place of the oat flour if needed.
Skip the icing - For a more rustic, homey cake, you can leave off the cream cheese icing. You can also stir in a ½ teaspoon of ground cinnamon for warmth or the zest of 1 lemon for a little citrus flavor.
StorageBecause this cake is topped with dairy-based icing, I recommend storing it, well-covered or in an airtight container, in the fridge rather than the counter. It will keep well in the fridge for up to 5 days.If you wish to freeze the cake, hold off on adding the icing. Wrap the cooled, whole cake in a layer of plastic wrap, then a layer of foil, and store it in the freezer for up to 3 months. Defrost the cake completely in the fridge before serving. If you wish, you can make the icing after the cake has thawed, then add it to the cake when you're ready to serve it. You can eat the cake at room temperature or straight from the fridge.