Place butter in a saucepan over low heat to melt; set aside. Place cottage cheese in a food processor or blender and pulse until pureed and no lumps remain; set aside.
Fit stand mixer with a paddle attachment and add melted butter, cottage cheese and sugar into stand mixer bowl. Mix on medium-low for 2 minutes or until well combined. Add in lemon and salt and mix until well combined. While mixer is running, add eggs in one at time and mix well after each addition. Turn mixer down to low and keep mixer running while gradually adding in flour.
Pour batter into prepared pan and bake at 350˚ until golden and a toothpick inserted comes out almost clean, approximately 60-70 minutes. Allow cake to cool in pan for 10 minutes. Turn out cake onto a cooling rack with topside down.
In small bowl, whisk sugar with lemon juice; pour over cake, spreading over top and letting drip down sides. Sprinkle with crushed pistachios. Let cool completely before cutting.