Step 1

Arrange racks in top and bottom thirds of oven; preheat to 350°. Coat cake pans with nonstick spray; dust with flour. Whisk 2 3/4 cups flour and next 3 ingredients in a medium bowl. Using an electric mixer, beat sugar and butter at medium speed, occasionally scraping down sides of bowl, until smooth, 3–4 minutes. Add eggs one at a time, beating to blend between additions. Beat until light and fluffy, 2–3 minutes. Gradually beat in oil. Beat in dry ingredients at low speed in 3 additions, alternating with buttermilk in 2 additions, beginning and ending with dry ingredients. Divide among four 9" cake pans (about 2 generous cups batter per pan); smooth tops with a spatula.

Step 2

Bake until a tester inserted into center of cakes comes out clean, 22–27 minutes. Transfer pans to wire racks; let cool in pans for 5 minutes. Invert cakes onto racks, remove pans, and let cakes cool completely.

Step 3

Preheat oven to 350°. Place coconut chips in a single layer on a rimmed baking sheet lined with parchment paper. Toast until some of the chips are golden brown (some will remain white), 5–7 minutes; let cool completely. DO AHEAD: Can be made 3 days ahead. Store airtight at room temperature.

Step 4

Using an electric mixer, beat cream cheese and butter on high speed, occasionally scraping down sides of bowl, until smooth and creamy, 2–3 minutes. Add 1 1/2 Tbsp. Southern Comfort and salt; beat to blend, about 1 minute longer. Add sugar; beat on low speed to blend. Increase speed to high; beat until fluffy, 5–6 minutes.

Step 5

Using a long serrated knife, cut each cake in half horizontally (see page 106 for instructions). Place 1 layer, cut side up, on a cake stand or plate. Lightly brush with about 1/2 Tbsp. of Southern Comfort. Spread 1/2 cup frosting over. Repeat with remaining 7 layers, Southern Comfort, and frosting. Chill cake for 30 minutes. Leave remaining frosting at room temperature.

Step 6

Cover sides of chilled cake with frosting. Cover cake loosely with foil and chill overnight. DO AHEAD: Can be made 2 days ahead. Keep chilled. Let cake stand at room temperature for at least 30 minutes.

Step 7

Gently pat handfuls of toasted coconut chips over sides and top of cake and serve.