A new book dishes about the baking secrets, business deals and family life of the two sisters behind Georgetown Cupcake.

For nearly four years, Katherine Kallinis and Sophie Kallinis LaMontagne have been sating local sweet tooths through their bakery, Georgetown Cupcake (in Georgetown and Bethesda). Dessert devotees line up at local outposts for treats in flavors such as red velvet and chocolate hazelnut. They also watch the tasty triumphs and pastry pitfalls on TLC’s “D.C. Cupcakes,” which follows the sisters on their sugar-fueled journey. In “The Cupcake Diaries” ($24, HarperOne), Kallinis and Kallinis LaMontagne share memories, tips and recipes that have led them to the sweet spot they’re in today.

Were you surprised by how quickly your business took off?
Sophie Kallinis LaMontagne: When we opened, it was just the two of us. We really thought we’d have this quiet little neighborhood bakery. So on our opening day, we were shocked to see a line down the block. And then people came the next day and the next day. Something that we did resonated. We have over 300 employees now, and we ship our cupcakes all across the country.

Why do you think you’ve been so successful?
Katherine Kallinis: I think that one of the key factors has been to believe in ourselves, even if no one else does. Even our parents doubted us in the beginning. But we didn’t let that stop us.

You make 10,000 cupcakes a day. Do you ever get tired of it?
Kallinis LaMontagne: We still love what we do. We never do get sick of cupcakes. We have new flavors all the time, and we literally eat cupcakes every day.

Your book is filled with lots of childhood and family memories. How have you been inspired by those?
Kallinis: When we were growing up, it was all about food and family. Everyone came together in the kitchen. We learned how to bake from our grandmother, how to make something and convey that you love someone by making it for them.

Can anyone make a cupcake? What are some tips or key pieces of equipment to have on hand?
Kallinis: If you have a stand mixer, that’s always easiest, but you can always use a hand mixer, too. And sometimes having an ice cream scoop is helpful to measure out the batter so each cupcake comes out evenly.

What are your favorite kinds of cupcakes to eat at this time of year?
Kallinis LaMontagne: Pumpkin spice, for both of us. It’s a pumpkin cupcake with maple cream cheese frosting; the recipe is in the book.

What do you think a person’s cupcake choice says about her?
Kallinis LaMontagne: It does speak to their personality. People who go for vanilla-vanilla are more conservative. People who go for lemon berry are more spunky. And people who go for red velvet are definitely romantic.

Say someone wants to incorporate cupcakes into a Thanksgiving or Christmas celebration. How would you suggest they do that?
Kallinis LaMontagne: The pumpkin spice and caramel apple cupcakes are great for Thanksgiving. It’s an individual portion you can serve after dinner, something that’s sweet and not overwhelming.

Caramel Apple Cupcakes

Makes 18 cupcakes

2 1/2 cups all-purpose flour
3 teaspoons baking powder
1 teaspoon ground cinnamon
1/2 teaspoon salt
16 tablespoons unsalted butter, at room temperature
2 cups sugar
4 large eggs, at room temperature
1⁄3 cup hot water
2 1/2 cups freshly grated apples (4 to 5 medium ones)
Vanilla Cream-Cheese Frosting (recipe below)

Preheat the oven to 350 F. Line a standard cupcake pan with twelve paper baking cups and a second pan with six baking cups, or grease pans with butter if not using baking cups.

Sift together flour, baking powder, cinnamon and salt on a sheet of parchment paper and set aside.

Place butter in the bowl of a stand mixer or in a bowl with a handheld electric mixer. Beat on medium speed until fluffy. Stop to add the sugar; beat on medium speed until well incorporated, approximately three to five minutes.

Add eggs one at a time, mixing slowly on medium after each addition.

Reduce the speed to low. Add one-third of the flour mixture to the butter mixture, then gradually add one third of the hot water, beating until well incorporated. Add another third of the flour mixture, followed by one third of the hot water. Stop to scrape down the bowl as needed. Add the remaining flour mixture, followed by the remaining hot water, and beat just until combined.

Using a spatula, fold the grated apple into the batter. Take care not to over-mix the batter. If you over-mix it, the cupcakes will not be light and fluffy but instead very dense.

Use a standard-size ice-cream scoop to fill each baking cup with batter, so the cups are two-thirds full. Bake for 18 to 20 minutes (start checking at 15 minutes) or until a toothpick inserted into the center of a cupcake comes out clean. After five minutes, transfer the cupcakes to a wire rack to cool completely for approximately 20 minutes.

Cool the cupcakes at room temperature. Putting them in the refrigerator to cool can dry out the cake.

Vanilla Cream-Cheese Frosting

4 tablespoons unsalted butter, at room temperature (european style recommended)
4 cups confectioners’ sugar, sifted
¼ teaspoon pure vanilla extract
6 ounces cream cheese, at room temperature

Place all ingredients in the bowl of an electric mixer fitted with the paddle attachment; beat until well combined. Be sure to beat on high speed at the very end for at least 2 minutes to ensure that the frosting is light and fluffy.