To make the dough:
Crack eggs into the bowl of a stand mixer (if you're using a whisk or a beater, use a large mixing bowl). Add sugar and salt, then using the whisk attachment turn the mixer to medium-high. Whip until the egg mixture has tripled in volume. Slow the mixer, then add vanilla and melted butter, in a slow drizzle. (Make sure the butter has cooled a bit before adding it to the eggs.) Let the batter mix completely, then add flour. Mix until smooth, transfer to a clean bowl, and cover and chill for at least 2 hours.
You can make the dough a day or two in advance.
To make the topping:
Melt ingredients in a pot and bring to a boil. Cook for one minute, then remove from heat. Transfer the mixture to a container and whisk periodically until cooled. Whisking will keep the butter from floating to the top.
Preheat oven to 325F.
Cut and core the pears, then slice them into 1/2-inch thick pieces. Toss the pear slices in lemon zest and a bit of lemon juice. Add sugar and a pinch of salt, then let the pears sit for about 30 minutes.
Meanwhile, toast the sliced almonds in the oven until golden brown, about 10-15 minutes.
Pour an even layer of the toppings into a 9-inch cake mold. Sprinkle the topping with toasted almonds, then pears. Spoon the dough on top of the pears as evenly as possible, then bake until the top is golden brown.
Let the cooked cake cool. Then, when you're ready to serve, warm it up for 5 minutes and flip it onto a serving dish.