Let the oven preheat to 350°F (177°C). Prepare two 12-count muffin pans and place 18 liners. Mix flour, baking soda, baking powder, and salt in a bowl and put it aside.
Put ¾ cup of butter in a microwave-safe bowl and microwave it to melt the butter. Stir in 1 ½ cups of sugar to create a gritty mixture. Let it cool down for 2-3 minutes before tossing in yogurt, milk, egg, and vanilla extract. Then, gradually mix it with the dry ingredients in step 1 to create a thick batter.
Whisk 3 teaspoons of ground cinnamon and the remaining ¾ cup of sugar in another bowl. Alternate between 2 tablespoons of batter and 1 teaspoon of sugar-cinnamon mixture until filling up to ¾ of each liner, finishing with a teaspoon of sugar-cinnamon mix.
Bake for 19 to 21 minutes and let them cool down.
Beat 1 cup of butter on high speed using a handheld or electric mixer for 1 minute.
Dump in cream, confectioners’ sugar, and vanilla extract and continue mixing on low speed for 30 more seconds. Then, beat them at high speed for 3 minutes. Toss in more sugar to fix too thick frosting and cream for too thin one. Sprinkle some salt if it’s too sweet.
Divide the frosting into 2 halves and mix one part with 1 ½ tablespoons of cinnamon. Fill both parts into a piping bag with a piping tip and frost the cupcakes.