Let’s break down the process into easy-to-follow steps.

1. Make the Crust:

• Preheat the oven to 350°F (175°C).
• Combine the cracker crumbs, sugar, and melted butter in a medium bowl. Mix with a fork until the crumbs are well coated and stick together when pinched.
• Press the mixture into the bottom and up the sides of a 9-inch pie plate.
• Bake until set, about 10 minutes.
• Set aside to cool slightly, about 10 minutes.

2. Make the Filling:

• Whisk together the condensed milk, lemon juice, egg yolks, and lemon zest in a medium bowl until combined.
• Pour the filling into the pre-baked and slightly cooled crust.

3. Bake the Pie:

• Bake until the center is set but still slightly jiggly, about 15 minutes.

4. Cool and Chill:

• Let cool for 30 minutes, then refrigerate until chilled, about 2 hours. This chilling time is essential for allowing the filling to set completely.

5. Make the Topping (Before Serving):

• Beat the heavy cream, powdered sugar, and vanilla in a large bowl with a mixer on medium speed until soft peaks form.

6. Assemble and Serve: Dollop the whipped cream on the center of the pie and serve.

These instructions are clear and easy to do.