Tools: 9×13 metal pan, parchment, mixer, long serrated knife, ruler, rolling pin, offset spatula, pizza cutter, cake board, small paintbrush, plastic wrap.
Steps
Batter.Day 1 · 20 min Heat oven to 325°F. Grease pan, line bottom with parchment, grease again. Beat butter and sugar 3–4 min until pale. Add eggs one at a time, then vanilla. Whisk flour, baking powder and salt separately. On low, add flour in 3 parts alternating with milk in 2, starting and ending with flour. Stop when no dry streaks remain.
Bake and cool.Day 1 · 45–55 min + cooling Spread evenly. Bake until a skewer in the center comes out clean; check at 45 min. Cool in pan 15 min, turn onto a rack, peel off parchment, cool completely. Wrap in plastic and refrigerate overnight.
Level and cut.Day 2 · 15 min Freeze 30 min. With a serrated knife, level the top to 1¾ in tall, trim the crust off all four sides, and cut a 9 × 6½ in rectangle. Use a ruler.
Shape the spine (optional).5 min Round the top and bottom edges of one long side. Carve a very shallow inward curve on the opposite long side. Fine to skip on a first attempt.
Crumb coat.10 min + 20 min chill Beat butter smooth, add powdered sugar and milk, beat 2 min. Spread a thin, flat layer over the top and all sides. Refrigerate 20 min until firm.
Pages.20 min Knead white fondant, roll ⅛ in thick on cornstarch. Cut strips the height of the cake. Press onto the front long side and both short ends; leave the spine bare. Trim flush, smooth seams.
Score page lines.15 min Press a ruler edge lightly into the strips every ⅛ in to make straight horizontal lines. Press, don't drag.
Cover.25 min Roll navy fondant ⅛ in thick, about 15 × 11 in.
Bottom: cake size plus ⅛ in on the three page sides. Lay on board, set cake on it flush with the spine.
Top + spine: one piece. Press onto spine, fold over the top, smooth from spine outward.
Trim open edges so the cover overhangs the pages by ⅛ in. This is what makes it read as a hardcover.
Finish.15 min Press a hinge groove ½ in in from the spine on the top cover. Write title and author in gold. Optional: dry-brush luster dust on page edges. Brush off visible cornstarch.
Watch for
Flour: spoon into the cup and level. Scooping packs 15–25% extra and makes a dry cake that crumbles when carved. A scale removes the guesswork (3¼ cups = 390 g).
Bake time varies; dark or glass pans run faster. Trust the skewer.
Chill or freeze before every cut. Warm cake crumbles.
Use only products labeled edible for gold. "Non-toxic" is not food-safe.
Don't refrigerate after fondant is on. Store in a cool room, loosely covered, up to 2 days.