Peel and core the Granny Smith and Honeycrisp apples, then cut them into slices with natural variation in thickness. Place the sliced apples loosely in a cream-colored ceramic baking dish so some pieces overlap while others sit at different angles. Measure the lemon juice, brown sugar, cinnamon, nutmeg, salt and vanilla separately before adding them. At this stage the apples should still look firm, pale and fresh with slightly irregular edges.

Pour the lemon juice and vanilla over the apple slices, then scatter the brown sugar, cinnamon, nutmeg and salt across them. The spices should land unevenly at first, leaving darker cinnamon patches and visible areas of plain apple. Mix the slices until most surfaces are lightly coated but don't force every piece to look identical. The apples should begin looking slightly glossy as the sugar and juices cling to their surfaces and gather lightly between overlapping pieces.

Combine the all-purpose flour, rolled oats, brown sugar, cinnamon and salt. Add the butter and work it through until the dry mixture changes into irregular crumbs with a mix of tiny sandy pieces and larger rough clusters. The mixture shouldn't become smooth or uniform. Some butter should disappear into the flour while a few small buttery patches remain visible, creating the uneven crumble texture that will later develop crisp and browned areas.

Settle the seasoned apples naturally across the cream-colored ceramic baking dish without pressing them into neat rows. Pour any cinnamon-sugar liquid remaining among the apples over the fruit so it collects more heavily in some spaces than others. Scatter the oat crumble loosely over the apples. Leave a few small gaps where pieces of fruit remain visible and allow some larger crumble clusters to sit beside finer crumbs so the topping looks homemade rather than perfectly covered.

The assembled dessert now appears transformed, with the apple slices softened and slightly collapsed while still retaining visible curved shapes. Their juices have combined with the sugar into a thicker amber cinnamon sauce that appears more concentrated around some edges and between certain fruit pieces. The oat topping has changed from pale crumbs to irregular golden-brown clusters. Some areas are deeply toasted while others remain lighter, and melted butter has created rough crisp patches rather than an evenly colored surface.

Spoon a generous portion of the finished apple crisp onto a matte cream ceramic dessert plate. Let the serving fall naturally so some oat clusters remain on top while others tumble toward the edges and glossy softened apple slices peek through unevenly. Add a scoop of vanilla bean ice cream beside the warm crisp. It should begin softening where it touches the apples, creating a small irregular creamy melt while the crisp remains visibly golden, caramelized and homemade.