Preheat oven to 350°F. Prepare two 10 in. round baking pans with vegetable pan spray. Line bottom of pans with parchment paper.
In large bowl, sift together flour, baking powder and salt. In large bowl, beat butter with electric mixer until smooth, about 2 minutes. Gradually add sugar, beating until very light and fluffy, about 3 minutes. Scrape down sides of bowl. Add vanilla and eggs, one at a time, scraping down sides of bowl after each addition. Add flour in four additions, alternating with milk, beating until just combined. Divide evenly between the pans; smooth the tops.
Bake 33-36 minutes or until toothpick inserted in center of cake shows a few moist crumbs. Cool in pans 5 minutes. Remove from pans; peel away parchment paper and cool completely.
Line two 10 in. pans with plastic wrap, letting it hang over the edges. Trim the dome from the top of each cake. Put cakes back in pans. In large bowl, whisk together all remaining liquids until well combined. Pour evenly over tops of both cakes. Fold plastic wrap over tops and refrigerate overnight.
To assemble cake, remove one cake layer from the pan by pulling up on the plastic wrap. Transfer to a cake board or serving plate. Spread a thin layer of buttercream icing evenly over the layer. Cover completely with sliced berries. Cover with second cake layer. Ice top and sides of cake with buttercream.
Makes about 30 servings.