The source files for the UE5 Blueprint/C++ interop tutorial at https://www.youtube.com/watch?v=ejGfHtgGOOI

SomeObject.cpp

#include "SomeObject.h"

DEFINE_LOG_CATEGORY_STATIC(SomeObjectSub, Log, All);

void USomeObject::HelloFromABlueprint(int someArgument) {
    UE_LOG(SomeObjectSub, Warning, TEXT("Hello called from a blueprint down to C++! With arguemnt: %d"), someArgument);

    CallBlueprintFromCpp(someArgument);
    CallBlueprintNativeEvent(someArgument);
}

void USomeObject::CallBlueprintNativeEvent_Implementation(int someArgument) {
    UE_LOG(SomeObjectSub, Warning, TEXT("Called a native blueprintable event: %d"), someArgument);
}

SomeObject.h

#pragma once

#include "CoreMinimal.h"
#include "SomeObject.generated.h"

UCLASS(Blueprintable)
class USomeObject : public UObject {
    GENERATED_BODY()

public:
    UFUNCTION(BlueprintCallable)
    void HelloFromABlueprint(int someArgument);

    UFUNCTION(BlueprintImplementableEvent)
    void CallBlueprintFromCpp(int someArgument);

    UFUNCTION(BlueprintNativeEvent)
    void CallBlueprintNativeEvent(int someArgument);
};