For the Cake:

Preheat your oven to 350°F. Lightly spread butter into two 9-inch round cake pans, then line the bottoms with parchment paper. After placing the parchment paper, dust the inside of the pans lightly with flour to avoid the cake sticking. Shake out excess flour and set aside.
In a large mixing bowl, whisk together the flour, baking powder, and salt. Set the bowl aside.
In your stand mixer, cream butter and sugar together for about 2-3 minutes, until the mixture is smooth.
In your stand mixer, cream butter and sugar together for about 2-3 minutes, until the mixture is smooth.
Add oil and vanilla extract and combine.
Start your mixer on low, and add 1/3 of the dry ingredients to the bowl, mixing until combined. Then add half of the milk, mixing until combined. Add the next 1/3 of the dry ingredients, then the rest of the milk, and then the last 1/3 of the dry ingredients. Mix slowly, do not over-mix the batter.
Divide the batter evenly between your 9 x 9 pans. Bake for 20-24 minutes, or until the top is springy, or a toothpick inserted into the center comes out clean. Let the cakes cool completely.

For the Frosting:

In a large mixing bowl, use an electric mixer to beat the softened butter until fluffy and smooth.
Gradually add the powdered sugar, about ⅓ cup at a time, mixing on low speed. Be sure to scrape down the sides and bottom of the bowl as you go.
Mix in the vanilla extract and salt.
Slowly pour in the milk or heavy cream while continuing to mix on low.
Once everything is incorporated, turn the mixer to high and beat for 30 seconds to 3 minutes, or until the frosting is light, fluffy, and creamy.
Adjust the consistency as needed — add more powdered sugar for a thicker frosting or more milk/cream to thin it out. I recommend a thicker frosting for this cake, since the strawberries will have to "stick" to it on the top of the cake.

To Frost the Cake:

If your cake layers have domed tops, you can use a serrated knife to trim them flat. This helps the layers stack evenly, but don’t stress if they’re not perfect—it’s a homemade cake!
Place one of the cake layers on your serving plate or cake stand, flat side down. You can add a small dab of frosting underneath to keep it from sliding around.
Scoop about ⅓ of your frosting onto the first layer and spread it evenly with an offset spatula or butter knife, going all the way to the edges.
Spoon a generous amount of the strawberry filling and gently spread over the frosting layer.
Gently place the second cake layer on top, flat side up this time, to give you a nice, even surface for frosting.
Spoon the remaining frosting onto the top of the cake and spread it out toward the edges. Next, place a ring of cut strawberries around the outer edge of the top of the cake. This will help keep the rest of the strawberry filling in place. Pour the remaining strawberry filling on top of the cake in the center. You can go for a clean look or keep it rustic—totally up to you!

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