Preheat oven to 350°F and set aside a greased 9”x13” pan.
In a bowl, sift together the all-purpose flour, baking powder, and salt. Set aside.
In a large bowl, whisk the butter and sugar until light and fluffy, about 3 minutes.
Add eggs one at a time, mixing well after each addition. Whisk in vanilla.
Add flour mixture and gently mix until thoroughly combined.
Pour batter and spread evenly into the prepared pan. Bake until an inserted toothpick comes out clean, about 30 minutes. Remove cake and allow it to cool for 15 minutes, then transfer to a wire rack to cool completely.
Reduce oven temperature to 300°F.
Once cooled completely, trim and discard the edges (or enjoy them!). With the longer side facing you, cut the cake down the center horizontally, followed by slicing into ½”-thick slices.
Line the sliced cake on an ungreased baking sheet, sliced side-up, and bake for 15 minutes. Flip the slices over and bake for an additional 15minutes.
Remove from the oven and cool completely. Store in an airtight container at room temperature.