Preheat the oven to 375 F and line a baking sheet with parchment paper. Place the slices of baguette on the baking sheet. Brush both sides with olive oil. Bake for 5 minutes, flip and bake for another 5 minutes. Remove the crostini to a serving tray and set aside.
Make the whipped ricotta
In a food processor or high speed blender add the ricotta, salt, pepper, lemon zest and olive oil. Blend on high speed until smooth and creamy, about 1-2 minutes, scraping down the sides of the food processor as needed. Set aside in the fridge until ready to assemble the crostini.
Make the apples
Add 2 tablespoons of butter to a medium-sized pan over medium heat. When the butter is melted, add the diced apple, ground cinnamon and ground nutmeg and stir to combine. Cook the apples over medium heat, stirring often, until fork tender and softened, about 8-10 minutes. *If you notice the apples starting to brown too much, turn to medium-low heat*Once the apples are softened, add the vanilla extract and maple syrup to the pan and cook for 2 more minutes, stirring a few times. Remove the pan from the heat and spoon the apples into a bowl to cool.
Assemble the crostini
Once the apples are fully cooled, assemble the crostini. Spread the whipped ricotta (or you can pipe the ricotta onto the crostini for a fancier presentation) onto the crostini, dividing evenly between the slices. Spoon the cooled maple apples onto the ricotta layer and then garnish with walnuts and fresh thyme leaves.
Notes
Make sure to use full fat (whole milk) ricotta for the best whipped ricotta texture.
A good substitute for Honey Crisp apples are Ambrosia, Fuji or Pink Lady apples.
Make the whipped ricotta ahead of time and store in the fridge for up to 1 day. Keep in the fridge until ready to assemble the appetizer.