Start by preheating your oven to 350°F and setting out a 9-inch pie dish. I don't bother greasing mine since the butter in the topping keeps things from sticking. Getting the oven ready first means you're not waiting around once your filling and topping are done.
Peel and core all five pears, then slice them into strips or cubes, whichever you prefer. I usually slice mine into strips and cut each one in half so they cook evenly. Firm pears actually work better here since they hold their shape instead of turning mushy in the oven.
Toss the sliced pears into a large mixing bowl with the lemon juice, maple syrup, brown sugar, cinnamon, ginger, salt, vanilla, and cornstarch. Stir everything together until the pears are evenly coated. Set this bowl aside while you make the crumble topping.
In a separate bowl, mash the softened butter and sugar together with a fork until well combined. Add in 1 cup of flour first, along with the cinnamon and salt, mixing until it looks crumbly. If it still feels too wet, sprinkle in a bit more flour, up to a ¼ cup extra.
Pour the coated pears into your pie dish, spreading them out evenly. Scatter the crumble topping over the top in an even layer. Bake, uncovered, for 45 to 50 minutes, until the topping turns golden brown and the filling bubbles at the edges.
Let the crumble rest for about 10 minutes once it's out of the oven so the juices have time to settle. This makes it easier to scoop without everything running together. Serve warm with a scoop of vanilla ice cream or a dollop of whipped cream on top.