PREPARE THE TOFFEE BASE:
1. Preheat oven to 350°F (175°C). Position rack in center of oven.
2. Line bottom of 9x9-inch square baking pan with parchment paper (leaving sides unlined helps with clean removal).
3. In medium saucepan, melt butter with brown sugar over medium heat, stirring constantly until butter is fully melted and sugar begins to dissolve.
4. Add heavy cream and sea salt, stirring continuously until mixture is smooth and begins to bubble.
5. Continue cooking 2-3 minutes, stirring constantly, until mixture slightly thickens and reaches 220°F (104°C) on candy thermometer (mixture should coat back of spoon).
6. Pour hot toffee mixture into prepared square pan, using offset spatula to spread evenly across bottom.

ARRANGE THE APPLES:
7. Peel, core, and slice apples into uniform 1/4-inch thick slices.
8. Arrange apple slices in neat overlapping pattern over toffee layer, working from outer edges toward center to create modern geometric design (can do concentric squares or straight rows).
9. Ensure apples cover toffee completely with minimal gaps.
10. Sprinkle arranged apples evenly with 1 teaspoon cinnamon and 1/4 teaspoon nutmeg.
11. Press apples gently into toffee with clean fingertips to ensure good contact and eliminate air pockets.

MAKE THE SPICED CAKE BATTER:
12. In medium bowl, sift together flour, baking powder, salt, cinnamon, ginger, nutmeg, and cloves. Set aside.
13. In large bowl using electric mixer, cream softened butter and granulated sugar together on medium-high speed until light, fluffy, and pale in color, about 4-5 minutes (mixture should look almost white and increase in volume).
14. Beat in eggs one at a time on medium speed, mixing well after each addition and scraping down bowl sides with spatula between additions.
15. Add vanilla extract and mix on low speed until just incorporated.
16. In small measuring cup, combine milk with apple cider or apple juice.
17. With mixer on low speed, add dry ingredients and milk mixture alternately in three additions: one-third of flour mixture, half of milk mixture, one-third of flour mixture, remaining milk mixture, remaining flour mixture.
18. Mix on low speed just until combined after each addition, scraping down bowl as needed (do not overmix or cake will be tough).
19. Final batter should be smooth, thick, and pourable.

ASSEMBLE AND BAKE:
20. Using large spoon or ladle, carefully dollop batter over arranged apples, starting from edges and working toward center to minimize disturbing apple arrangement.
21. Spread batter gently with offset spatula to cover apples completely and evenly, using gentle back-and-forth motions.
22. Smooth top of batter with spatula for even baking and level surface.
23. Bake 40-45 minutes until top is golden brown and springs back when lightly touched in center.
24. Test for doneness: insert toothpick or cake tester into center - should come out clean or with just a few moist crumbs (no wet batter).
25. Internal temperature should reach 200-205°F (93-96°C) when measured with instant-read thermometer.

INVERT AND SERVE:
26. Remove cake from oven and cool in pan on wire rack for exactly 10 minutes (critical timing - too short and cake breaks apart, too long and toffee hardens making removal difficult).
27. Run thin knife or offset spatula around all four edges of pan to completely loosen cake from sides.
28. Place large serving platter or cutting board upside down over top of cake pan.
29. Using oven mitts or kitchen towels, hold platter and pan together firmly and quickly invert in one confident, smooth motion.
30. Leave inverted pan in place for 2-3 minutes to allow all toffee to drip down onto cake surface.
31. Gently lift and remove pan to reveal glossy toffee-coated apple topping.
32. If any apple slices stick to pan, carefully remove with spatula and place back on cake surface in original pattern.
33. Allow cake to cool slightly, about 10-15 minutes, so toffee sets enough to slice cleanly without running.
34. Cut into 9 or 12 neat squares using sharp knife, wiping blade clean between cuts for professional edges.
35. Serve warm or at room temperature.

STORAGE AND SERVING:
Store covered at room temperature up to 2 days, or refrigerate up to 4 days
Reheat individual slices in microwave for 20-30 seconds or in 300°F oven for 5-10 minutes
Best served slightly warm with vanilla ice cream, whipped cream, or crème fraîche
Cake can be made ahead and inverted just before serving for best presentation