Arrange a rack in the middle of the oven and heat the oven to 375ºF. Line a rimmed baking sheet with parchment paper.
Halve 2 medium D’Anjou pears lengthwise. Halve, core, and thinly slice 2 medium Honeycrisp apples (no need to peel the pears or apples). Place the pears and apples in a large bowl.
Add 1/4 cup of the maple syrup, 1 tablespoon olive oil, 1 teaspoon ground cinnamon, 1/2 teaspoon nutmeg, and 1/4 teaspoon ground allspice, and toss until the fruit are fully coated.
Transfer to the baking sheet and arrange in the single layer with the pears cut-side up. Bake until the fruit is golden-brown and knife tender, 20 to 25 minutes.
Transfer 1 cup roasted apple slices to a medium bowl, add 1 tablespoon lemon juice, and crush everything together with a muddler (or one end of a rolling pin) until the apples are fully broken down. Add 2 cups filtered water and the remaining 2 tablespoons maple syrup, and stir until well combined.
Make the mocktails: For each drink, fill an 8-ounce glass halfway with crushed ice. Add 1/2 cup of the crushed apple mixture. Garnish with 1 roasted halved pear, a Honeycrisp apple slice, and a rosemary sprig. Top with ginger beer until the glass is filled.
Sip and Enjoy!