Preheat oven to 350 degrees Fahrenheit.
Add 4 tablespoons of butter into the 8x8 or similar baking dish and place in the oven to melt for about 3 minutes. Remove from oven when melted. Swirl the baking dish so butter evenly coats the bottom of the dish and set aside.
In a medium bowl, whisk the sugar and cornstarch together. Add the strawberries and lemon juice, stir to combine, and set aside.
Whisk together flour, baking powder, and sugar in a large bowl.
Add in milk and vanilla extract. Whisk until you have a smooth batter consistency. If the batter seems too thick, add a couple of tablespoons at a time of additional oat milk.
Pour batter evenly over the melted butter in the baking dish.
Spoon strawberries evenly on top of the batter using a slotted spoon, leaving the extra syrup in the bowl.
Baked for 35-40 minutes on the middle rack or until golden brown.
Remove from oven and let cobbler rest for a few minutes.
Spoon into a bowl and top with vanilla ice cream or whipped cream if desired.